A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called secret_hash and the other session_id. Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating "secret_hash" of different size than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used again during second key re-exchange.

The remote NewStart CGSL host, running version MAIN 6.02, has libssh packages installed that are affected by multiple vulnerabilities:

  - The RAND_bytes function in libssh before 0.6.3, when forking is enabled, does not properly reset the state     of the OpenSSL pseudo-random number generator (PRNG), which causes the state to be shared between children     processes and allows local users to obtain sensitive information by leveraging a pid collision.
    (CVE-2014-0017)

  - A vulnerability was found in libssh's server-side state machine. A malicious client could create channels     without first performing authentication, resulting in unauthorized access. (CVE-2018-10933)

  - A flaw was found with the libssh API function ssh_scp_new(). A user able to connect to a server using SCP     could execute arbitrary command using a user-provided path, leading to a compromise of the remote target.
    (CVE-2019-14889)

  - A flaw was found in libssh. A NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL.
    (CVE-2020-16135)

  - A flaw was found in the way libssh handled AES-CTR (or DES ciphers if enabled) ciphers. The server or     client could crash when the connection hasn't been fully initialized and the system tries to cleanup the     ciphers when closing the connection. The biggest threat from this vulnerability is system availability.
    (CVE-2020-1730)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

This plugin has been deprecated as it does not adhere to established standards for this style of check.

The remote SUSE Linux SLES12 / SLES_SAP12 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2024:0539-1 advisory.

  - A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
    When the libssh SCP client connects to a server, the scp command, which includes a user-provided path, is     executed on the server-side. In case the library is used in a way where users can influence the third     parameter of the function, it would become possible for an attacker to inject arbitrary commands, leading     to a compromise of the remote target. (CVE-2019-14889)

  - libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL.
    (CVE-2020-16135)

  - A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully     initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat     from this vulnerability is system availability. (CVE-2020-1730)

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared     secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as     an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked     as long as these buffers were same. But the key re-exchange operation can also change the key exchange     method, which can be based on hash of different size, eventually creating secret_hash of different size     than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used     again during second key re-exchange. (CVE-2021-3634)

  - A NULL pointer dereference was found In libssh during re-keying with algorithm guessing. This issue may     allow an authenticated client to cause a denial of service. (CVE-2023-1667)

  - A vulnerability was found in libssh, where the authentication check of the connecting client can be     bypassed in the`pki_verify_data_signature` function in memory allocation problems. This issue may happen     if there is insufficient memory or the memory usage is limited. The problem is caused by the return value     `rc,` which is initialized to SSH_ERROR and later rewritten to save the return value of the function call     `pki_key_check_hash_compatible.` The value of the variable is not changed between this point and the     cryptographic verification. Therefore any error between them calls `goto error` returning SSH_OK.
    (CVE-2023-2283)

  - The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other     products, allows remote attackers to bypass integrity checks such that some packets are omitted (from the     extension negotiation message), and a client and server may consequently end up with a connection for     which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because     the SSH Binary Packet Protocol (BPP), implemented by these extensions, mishandles the handshake phase and     mishandles use of sequence numbers. For example, there is an effective attack against SSH's use of     ChaCha20-Poly1305 (and CBC with Encrypt-then-MAC). The bypass occurs in chacha20-poly1305@openssh.com and     (if CBC is used) the -etm@openssh.com MAC algorithms. This also affects Maverick Synergy Java SSH API     before 3.1.0-SNAPSHOT, Dropbear through 2022.83, Ssh before 5.1.1 in Erlang/OTP, PuTTY before 0.80,     AsyncSSH before 2.14.2, golang.org/x/crypto before 0.17.0, libssh before 0.10.6, libssh2 through 1.11.0,     Thorn Tech SFTP Gateway before 3.4.6, Tera Term before 5.1, Paramiko before 3.4.0, jsch before 0.2.15,     SFTPGo before 2.5.6, Netgate pfSense Plus through 23.09.1, Netgate pfSense CE through 2.7.2, HPN-SSH     through 18.2.0, ProFTPD before 1.3.8b (and before 1.3.9rc2), ORYX CycloneSSH before 2.3.4, NetSarang     XShell 7 before Build 0144, CrushFTP before 10.6.0, ConnectBot SSH library before 2.2.22, Apache MINA sshd     through 2.11.0, sshj through 0.37.0, TinySSH through 20230101, trilead-ssh2 6401, LANCOM LCOS and     LANconfig, FileZilla before 3.66.4, Nova before 11.8, PKIX-SSH before 14.4, SecureCRT before 9.4.3,     Transmit5 before 5.10.4, Win32-OpenSSH before 9.5.0.0p1-Beta, WinSCP before 6.2.2, Bitvise SSH Server     before 9.32, Bitvise SSH Client before 9.33, KiTTY through 0.76.1.13, the net-ssh gem 7.2.0 for Ruby, the     mscdex ssh2 module before 1.15.0 for Node.js, the thrussh library before 0.35.1 for Rust, and the Russh     crate before 0.40.2 for Rust. (CVE-2023-48795)

  - A flaw was found in libssh. By utilizing the ProxyCommand or ProxyJump feature, users can exploit     unchecked hostname syntax on the client. This issue may allow an attacker to inject malicious code into     the command of the features mentioned through the hostname parameter. (CVE-2023-6004)

  - A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by     different supported crypto backends. The return values from these were not properly checked, which could     cause low-memory situations failures, NULL dereferences, crashes, or usage of the uninitialized memory as     an input for the KDF. In this case, non-matching keys will result in decryption/integrity failures,     terminating the connection. (CVE-2023-6918)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2024:0525-1 advisory.

  - A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
    When the libssh SCP client connects to a server, the scp command, which includes a user-provided path, is     executed on the server-side. In case the library is used in a way where users can influence the third     parameter of the function, it would become possible for an attacker to inject arbitrary commands, leading     to a compromise of the remote target. (CVE-2019-14889)

  - libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL.
    (CVE-2020-16135)

  - A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully     initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat     from this vulnerability is system availability. (CVE-2020-1730)

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared     secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as     an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked     as long as these buffers were same. But the key re-exchange operation can also change the key exchange     method, which can be based on hash of different size, eventually creating secret_hash of different size     than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used     again during second key re-exchange. (CVE-2021-3634)

  - A NULL pointer dereference was found In libssh during re-keying with algorithm guessing. This issue may     allow an authenticated client to cause a denial of service. (CVE-2023-1667)

  - A vulnerability was found in libssh, where the authentication check of the connecting client can be     bypassed in the`pki_verify_data_signature` function in memory allocation problems. This issue may happen     if there is insufficient memory or the memory usage is limited. The problem is caused by the return value     `rc,` which is initialized to SSH_ERROR and later rewritten to save the return value of the function call     `pki_key_check_hash_compatible.` The value of the variable is not changed between this point and the     cryptographic verification. Therefore any error between them calls `goto error` returning SSH_OK.
    (CVE-2023-2283)

  - The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other     products, allows remote attackers to bypass integrity checks such that some packets are omitted (from the     extension negotiation message), and a client and server may consequently end up with a connection for     which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because     the SSH Binary Packet Protocol (BPP), implemented by these extensions, mishandles the handshake phase and     mishandles use of sequence numbers. For example, there is an effective attack against SSH's use of     ChaCha20-Poly1305 (and CBC with Encrypt-then-MAC). The bypass occurs in chacha20-poly1305@openssh.com and     (if CBC is used) the -etm@openssh.com MAC algorithms. This also affects Maverick Synergy Java SSH API     before 3.1.0-SNAPSHOT, Dropbear through 2022.83, Ssh before 5.1.1 in Erlang/OTP, PuTTY before 0.80,     AsyncSSH before 2.14.2, golang.org/x/crypto before 0.17.0, libssh before 0.10.6, libssh2 through 1.11.0,     Thorn Tech SFTP Gateway before 3.4.6, Tera Term before 5.1, Paramiko before 3.4.0, jsch before 0.2.15,     SFTPGo before 2.5.6, Netgate pfSense Plus through 23.09.1, Netgate pfSense CE through 2.7.2, HPN-SSH     through 18.2.0, ProFTPD before 1.3.8b (and before 1.3.9rc2), ORYX CycloneSSH before 2.3.4, NetSarang     XShell 7 before Build 0144, CrushFTP before 10.6.0, ConnectBot SSH library before 2.2.22, Apache MINA sshd     through 2.11.0, sshj through 0.37.0, TinySSH through 20230101, trilead-ssh2 6401, LANCOM LCOS and     LANconfig, FileZilla before 3.66.4, Nova before 11.8, PKIX-SSH before 14.4, SecureCRT before 9.4.3,     Transmit5 before 5.10.4, Win32-OpenSSH before 9.5.0.0p1-Beta, WinSCP before 6.2.2, Bitvise SSH Server     before 9.32, Bitvise SSH Client before 9.33, KiTTY through 0.76.1.13, the net-ssh gem 7.2.0 for Ruby, the     mscdex ssh2 module before 1.15.0 for Node.js, the thrussh library before 0.35.1 for Rust, and the Russh     crate before 0.40.2 for Rust. (CVE-2023-48795)

  - A flaw was found in libssh. By utilizing the ProxyCommand or ProxyJump feature, users can exploit     unchecked hostname syntax on the client. This issue may allow an attacker to inject malicious code into     the command of the features mentioned through the hostname parameter. (CVE-2023-6004)

  - A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by     different supported crypto backends. The return values from these were not properly checked, which could     cause low-memory situations failures, NULL dereferences, crashes, or usage of the uninitialized memory as     an input for the KDF. In this case, non-matching keys will result in decryption/integrity failures,     terminating the connection. (CVE-2023-6918)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote host is affected by the vulnerability described in GLSA-202312-05 (libssh: Multiple Vulnerabilities)

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared     secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as     an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked     as long as these buffers were same. But the key re-exchange operation can also change the key exchange     method, which can be based on hash of different size, eventually creating secret_hash of different size     than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used     again during second key re-exchange. (CVE-2021-3634)

  - A NULL pointer dereference was found In libssh during re-keying with algorithm guessing. This issue may     allow an authenticated client to cause a denial of service. (CVE-2023-1667)

  - A vulnerability was found in libssh, where the authentication check of the connecting client can be     bypassed in the`pki_verify_data_signature` function in memory allocation problems. This issue may happen     if there is insufficient memory or the memory usage is limited. The problem is caused by the return value     `rc,` which is initialized to SSH_ERROR and later rewritten to save the return value of the function call     `pki_key_check_hash_compatible.` The value of the variable is not changed between this point and the     cryptographic verification. Therefore any error between them calls `goto error` returning SSH_OK.
    (CVE-2023-2283)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Rocky Linux 8 host has packages installed that are affected by a vulnerability as referenced in the RLSA-2022:2031 advisory.

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared     secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as     an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked     as long as these buffers were same. But the key re-exchange operation can also change the key exchange     method, which can be based on hash of different size, eventually creating secret_hash of different size     than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used     again during second key re-exchange. (CVE-2021-3634)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Oracle Linux 8 host has packages installed that are affected by a vulnerability as referenced in the ELSA-2022-2031 advisory.

    - Fix CVE-2021-3634: Fix possible heap-buffer overflow when       rekeying with different key exchange mechanism

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote AlmaLinux 8 host has packages installed that are affected by a vulnerability as referenced in the ALSA-2022:2031 advisory.

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared     secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as     an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked     as long as these buffers were same. But the key re-exchange operation can also change the key exchange     method, which can be based on hash of different size, eventually creating secret_hash of different size     than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used     again during second key re-exchange. (CVE-2021-3634)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2022:2031 advisory.

    libssh is a library which implements the SSH protocol. It can be used to implement client and server     applications.

    The following packages have been upgraded to a later upstream version: libssh (0.9.6). (BZ#1896651)

    Security Fix(es):

    * libssh: possible heap-based buffer overflow when rekeying (CVE-2021-3634)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

    Additional Changes:

    For detailed information on changes in this release, see the Red Hat Enterprise Linux 8.6 Release Notes     linked from the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote CentOS Linux 8 host has packages installed that are affected by a vulnerability as referenced in the CESA-2022:2031 advisory.

  - libssh: possible heap-based buffer overflow when rekeying (CVE-2021-3634)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The version of Oracle MySQL Workbench installed on the remote Windows host is prior to 8.0.28. It is, therefore, affected by a vulnerability in the MySQL Workbench product of Oracle MySQL (component: Workbench: libssh). Supported versions that are affected are 8.0.27 and prior. Easily exploitable vulnerability allows low privileged attacker with network access via MySQL Workbench to compromise MySQL Workbench. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Workbench.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

According to the versions of the libssh package installed, the EulerOS Virtualization installation on the remote host is affected by the following vulnerabilities :

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared     secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as     an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked     as long as these buffers were same. But the key re-exchange operation can also change the key exchange     method, which can be based on hash of different size, eventually creating 'secret_hash' of different size     than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used     again during second key re-exchange. (CVE-2021-3634)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

According to the versions of the libssh package installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared     secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as     an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked     as long as these buffers were same. But the key re-exchange operation can also change the key exchange     method, which can be based on hash of different size, eventually creating 'secret_hash' of different size     than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used     again during second key re-exchange. (CVE-2021-3634)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

libssh security advisories :

The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called `secret_hash` and and the other `session_id`. Initially, both of them are the same, but after key re-exchange, previous `session_id` is kept and used as an input to new `secret_hash`.

Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating `secret_hash` of different size than the `session_id` has.

This becomes an issue when the `session_id` memory is zeroized or when it is used again during second key re-exchange.

The remote Debian 11 host has packages installed that are affected by a vulnerability as referenced in the dsa-4965 advisory.

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared     secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as     an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked     as long as these buffers were same. But the key re-exchange operation can also change the key exchange     method, which can be based on hash of different size, eventually creating secret_hash of different size     than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used     again during second key re-exchange. (CVE-2021-3634)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Ubuntu 20.04 LTS host has packages installed that are affected by a vulnerability as referenced in the USN-5053-1 advisory.

    It was discovered that libssh incorrectly handled rekeying. A remote attacker could use this issue to     cause libssh to crash, resulting in a denial of service, or possibly execute arbitrary code.

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
206832	NewStart CGSL MAIN 6.02 : libssh Multiple Vulnerabilities (NS-SA-2024-0052)	Nessus	NewStart CGSL Local Security Checks	critical
195761	RHEL 7 : libssh (Unpatched Vulnerability) (deprecated)	Nessus	Red Hat Local Security Checks	medium
195736	RHEL 8 : libssh (Unpatched Vulnerability) (deprecated)	Nessus	Red Hat Local Security Checks	medium
190835	SUSE SLES12 Security Update : libssh (SUSE-SU-2024:0539-1)	Nessus	SuSE Local Security Checks	high
190754	SUSE SLES15 Security Update : libssh (SUSE-SU-2024:0525-1)	Nessus	SuSE Local Security Checks	high
187202	GLSA-202312-05 : libssh: Multiple Vulnerabilities	Nessus	Gentoo Local Security Checks	medium
161351	Rocky Linux 8 : libssh (RLSA-2022:2031)	Nessus	Rocky Linux Local Security Checks	medium
161317	Oracle Linux 8 : libssh (ELSA-2022-2031)	Nessus	Oracle Linux Local Security Checks	medium
161108	AlmaLinux 8 : libssh (ALSA-2022:2031)	Nessus	Alma Linux Local Security Checks	medium
161015	RHEL 8 : libssh (RHSA-2022:2031)	Nessus	Red Hat Local Security Checks	medium
160923	CentOS 8 : libssh (CESA-2022:2031)	Nessus	CentOS Local Security Checks	medium
156885	Oracle MySQL Workbench < 8.0.28 (Jan 2022)	Nessus	Windows	medium
155501	EulerOS Virtualization 2.9.0 : libssh (EulerOS-SA-2021-2787)	Nessus	Huawei Local Security Checks	medium
155484	EulerOS Virtualization 2.9.1 : libssh (EulerOS-SA-2021-2753)	Nessus	Huawei Local Security Checks	medium
155268	EulerOS 2.0 SP9 : libssh (EulerOS-SA-2021-2691)	Nessus	Huawei Local Security Checks	medium
155128	EulerOS 2.0 SP9 : libssh (EulerOS-SA-2021-2716)	Nessus	Huawei Local Security Checks	medium
153827	FreeBSD : libssh -- possible heap-buffer overflow vulnerability (57b1ee25-1a7c-11ec-9376-0800272221cc)	Nessus	FreeBSD Local Security Checks	medium
152967	Debian DSA-4965-1 : libssh - security update	Nessus	Debian Local Security Checks	medium
152869	Ubuntu 20.04 LTS : libssh vulnerability (USN-5053-1)	Nessus	Ubuntu Local Security Checks	medium

Detections

Analytics

CVE-2021-3634

medium

Tenable Plugins

critical

medium

medium

high

high

medium

medium

medium

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