Use-after-free vulnerability in the gss_indicate_mechs function in lib/gssapi/mechglue/g_initialize.c in MIT Kerberos 5 (krb5) has unknown impact and attack vectors. NOTE: this might be the result of a typo in the source code.

The remote Oracle Linux 5 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2008-0164 advisory.

    [1.6.1-17.el5_1.1]
     - add preliminary patch to fix use of uninitialized pointer / double-free in        KDC (CVE-2008-0062,CVE-2008-0063) (#432620, #432621)
     - add backported patch to fix use-after-free in libgssapi_krb5      (CVE-2007-5901)        (#415321)
     - add backported patch to fix double-free in libgssapi_krb5 (CVE-2007-5971)        (#415351)
     - add preliminary patch to fix incorrect handling of high-numbered      descriptors        in the RPC library (CVE-2008-0947) (#433596)
     - fix storage of delegated krb5 credentials when they've been wrapped up in        spnego (#436460)
     - return a delegated credential handle even if the application didn't pass a        location to store the flags which would be used to indicate that      credentials        were delegated (#436465)
     - add patch to fall back to TCP kpasswd servers for kdc-unreachable,        can't-resolve-server, and response-too-big errors (#436467)
     - use the right sequence numbers when generating password-set/change      requests        for kpasswd servers after the first one (#436468)
     - backport from 1.6.3 to initialize a library-allocated get_init_creds_opt        structure the same way we would one which was allocated by the calling        application, to restore kinit's traditional behavior of doing a password        change right when it detects an expired password (#436470)

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

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

Sol Jerome discovered that the Kerberos kadmind service did not correctly free memory. An unauthenticated remote attacker could send specially crafted traffic to crash the kadmind process, leading to a denial of service. (CVE-2010-0629)

It was discovered that Kerberos did not correctly free memory in the GSSAPI library. If a remote attacker were able to manipulate an application using GSSAPI carefully, the service could crash, leading to a denial of service. (Ubuntu 8.10 was not affected.) (CVE-2007-5901, CVE-2007-5971)

It was discovered that Kerberos did not correctly free memory in the GSSAPI and kdb libraries. If a remote attacker were able to manipulate an application using these libraries carefully, the service could crash, leading to a denial of service. (Only Ubuntu 8.04 LTS was affected.) (CVE-2007-5902, CVE-2007-5972).

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

A flaw was found in the way the MIT Kerberos Authentication Service and Key Distribution Center server (krb5kdc) handled Kerberos v4 protocol packets. An unauthenticated remote attacker could use this flaw to crash the krb5kdc daemon, disclose portions of its memory, or possibly execute arbitrary code using malformed or truncated Kerberos v4 protocol requests. (CVE-2008-0062, CVE-2008-0063)

This issue only affected krb5kdc with Kerberos v4 protocol compatibility enabled, which is the default setting on Scientific Linux 4. Kerberos v4 protocol support can be disabled by adding 'v4_mode=none' (without the quotes) to the '[kdcdefaults]' section of /var/kerberos/krb5kdc/kdc.conf.

SL 3x only: A flaw was found in the RPC library used by the MIT Kerberos kadmind server. An unauthenticated remote attacker could use this flaw to crash kadmind. This issue only affected systems with certain resource limits configured and did not affect systems using default resource limits used by Scientific Linux 3. (CVE-2008-0948)

SL 4x and 5x only: Multiple memory management flaws were discovered in the GSSAPI library used by MIT Kerberos. These flaws could possibly result in use of already freed memory or an attempt to free already freed memory blocks (double-free flaw), possibly causing a crash or arbitrary code execution. (CVE-2007-5901, CVE-2007-5971)

SL 5x only: Jeff Altman of Secure Endpoints discovered a flaw in the RPC library as used by MIT Kerberos kadmind server. An unauthenticated remote attacker could use this flaw to crash kadmind or possibly execute arbitrary code. This issue only affected systems with certain resource limits configured and did not affect systems using default resource limits used by Red Hat Enterprise Linux 5. (CVE-2008-0947)

Updated krb5 packages that resolve several issues and fix multiple bugs are now available for Red Hat Enterprise Linux 5.

This update has been rated as having critical security impact by the Red Hat Security Response Team.

Kerberos is a network authentication system which allows clients and servers to authenticate to each other through use of symmetric encryption and a trusted third party, the KDC.

A flaw was found in the way the MIT Kerberos Authentication Service and Key Distribution Center server (krb5kdc) handled Kerberos v4 protocol packets. An unauthenticated remote attacker could use this flaw to crash the krb5kdc daemon, disclose portions of its memory, or possibly execute arbitrary code using malformed or truncated Kerberos v4 protocol requests. (CVE-2008-0062, CVE-2008-0063)

This issue only affected krb5kdc with Kerberos v4 protocol compatibility enabled, which is the default setting on Red Hat Enterprise Linux 4. Kerberos v4 protocol support can be disabled by adding 'v4_mode=none' (without the quotes) to the '[kdcdefaults]' section of /var/kerberos/krb5kdc/kdc.conf.

Jeff Altman of Secure Endpoints discovered a flaw in the RPC library as used by MIT Kerberos kadmind server. An unauthenticated remote attacker could use this flaw to crash kadmind or possibly execute arbitrary code. This issue only affected systems with certain resource limits configured and did not affect systems using default resource limits used by Red Hat Enterprise Linux 5. (CVE-2008-0947)

Red Hat would like to thank MIT for reporting these issues.

Multiple memory management flaws were discovered in the GSSAPI library used by MIT Kerberos. These flaws could possibly result in use of already freed memory or an attempt to free already freed memory blocks (double-free flaw), possibly causing a crash or arbitrary code execution. (CVE-2007-5901, CVE-2007-5971)

In addition to the security issues resolved above, the following bugs were also fixed :

* delegated krb5 credentials were not properly stored when SPNEGO was the underlying mechanism during GSSAPI authentication. Consequently, applications attempting to copy delegated Kerberos 5 credentials into a credential cache received an 'Invalid credential was supplied' message rather than a copy of the delegated credentials. With this update, SPNEGO credentials can be properly searched, allowing applications to copy delegated credentials as expected.

* applications can initiate context acceptance (via gss_accept_sec_context) without passing a ret_flags value that would indicate that credentials were delegated. A delegated credential handle should have been returned in such instances. This updated package adds a temp_ret_flag that stores the credential status in the event no other ret_flags value is passed by an application calling gss_accept_sec_context.

* kpasswd did not fallback to TCP on receipt of certain errors, or when a packet was too big for UDP. This update corrects this.

* when the libkrb5 password-routine generated a set-password or change-password request, incorrect sequence numbers were generated for all requests subsequent to the first request. This caused password change requests to fail if the primary server was unavailable. This updated package corrects this by saving the sequence number value after the AP-REQ data is built and restoring this value before the request is generated.

* when a user's password expired, kinit would not prompt that user to change the password, instead simply informing the user their password had expired. This update corrects this behavior: kinit now prompts for a new password to be set when a password has expired.

All krb5 users are advised to upgrade to these updated packages, which contain backported fixes to address these vulnerabilities and fix these bugs.

Multiple memory management flaws were found in the GSSAPI library used by Kerberos that could result in the use of already freed memory or an attempt to free already freed memory, possibly leading to a crash or allowing the execution of arbitrary code (CVE-2007-5901, CVE-2007-5971).

A flaw was discovered in how the Kerberos krb5kdc handled Kerberos v4 protocol packets. An unauthenticated remote attacker could use this flaw to crash the krb5kdc daemon, disclose portions of its memory, or possibly %execute arbitrary code using malformed or truncated Kerberos v4 protocol requests (CVE-2008-0062, CVE-2008-0063).

This issue only affects krb5kdc when it has Kerberos v4 protocol compatibility enabled, which is a compiled-in default in all Kerberos versions that Mandriva Linux ships prior to Mandriva Linux 2008.0.
Kerberos v4 protocol support can be disabled by adding v4_mode=none (without quotes) to the [kdcdefaults] section of /etc/kerberos/krb5kdc/kdc.conf.

A flaw in the RPC library as used in Kerberos' kadmind was discovered by Jeff Altman of Secure Endpoints. An unauthenticated remote attacker could use this vulnerability to crash kadmind or possibly execute arbitrary code in systems with certain resource limits configured;
this does not affect the default resource limits used by Mandriva Linux (CVE-2008-0947).

The updated packages have been patched to correct these issues.

This update incorporates fixes included in MITKRB5-SA-2008-001 (use of uninitialized pointer / double-free in the KDC when v4 compatibility is enabled) and MITKRB5-SA-2008-002 (incorrect handling of high-numbered descriptors in the RPC library). This update also incorporates less-critical fixes for a double- free (CVE-2007-5971) and an incorrect attempt to free non-heap memory (CVE-2007-5901) in the GSSAPI library. This update also fixes an incorrect calculation of the length of the absolute path name of a file when the relative path is known and the library needs to look up which SELinux label to apply to the file.

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

This update incorporates fixes included in MITKRB5-SA-2008-001 (use of uninitialized pointer / double-free in the KDC when v4 compatibility is enabled) and MITKRB5-SA-2008-002 (incorrect handling of high-numbered descriptors in the RPC library). This update also incorporates less-critical fixes for a double- free (CVE-2007-5971) and an incorrect attempt to free non-heap memory (CVE-2007-5901) in the GSSAPI library.

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

The remote host is running a version of Mac OS X 10.5 or 10.4 that does not have the security update 2008-002 applied. 

This update contains several security fixes for a number of programs.

ID	Name	Product	Family	Severity
67664	Oracle Linux 5 : Critical: / krb5 (ELSA-2008-0164)	Nessus	Oracle Linux Local Security Checks	critical
65123	Ubuntu 8.04 LTS / 8.10 / 9.04 : krb5 vulnerabilities (USN-924-1)	Nessus	Ubuntu Local Security Checks	critical
60373	Scientific Linux Security Update : krb5 on SL3.x, SL4.x, SL5.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	critical
43676	CentOS 5 : krb5 (CESA-2008:0164)	Nessus	CentOS Local Security Checks	critical
38056	Mandriva Linux Security Advisory : krb5 (MDVSA-2008:069)	Nessus	Mandriva Local Security Checks	critical
31670	Fedora 8 : krb5-1.6.2-14.fc8 (2008-2647)	Nessus	Fedora Local Security Checks	critical
31668	Fedora 7 : krb5-1.6.1-9.fc7 (2008-2637)	Nessus	Fedora Local Security Checks	critical
31616	RHEL 5 : krb5 (RHSA-2008:0164)	Nessus	Red Hat Local Security Checks	critical
31605	Mac OS X Multiple Vulnerabilities (Security Update 2008-002)	Nessus	MacOS X Local Security Checks	critical

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