GLSA-202310-12 : curl: Multiple Vulnerabilities

critical Nessus Plugin ID 182879

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Description

The remote host is affected by the vulnerability described in GLSA-202310-12 (curl: Multiple Vulnerabilities)

- A vulnerability exists in curl <7.87.0 HSTS check that could be bypassed to trick it to keep using HTTP.
Using its HSTS support, curl can be instructed to use HTTPS instead of using an insecure clear-text HTTP step even when HTTP is provided in the URL. However, the HSTS mechanism could be bypassed if the host name in the given URL first uses IDN characters that get replaced to ASCII counterparts as part of the IDN conversion. Like using the character UTF-8 U+3002 (IDEOGRAPHIC FULL STOP) instead of the common ASCII full stop (U+002E) `.`. Then in a subsequent request, it does not detect the HSTS state and makes a clear text transfer. Because it would store the info IDN encoded but look for it IDN decoded. (CVE-2022-43551)

- A use after free vulnerability exists in curl <7.87.0. Curl can be asked to *tunnel* virtually all protocols it supports through an HTTP proxy. HTTP proxies can (and often do) deny such tunnel operations.
When getting denied to tunnel the specific protocols SMB or TELNET, curl would use a heap-allocated struct after it had been freed, in its transfer shutdown code path. (CVE-2022-43552)

- A cleartext transmission of sensitive information vulnerability exists in curl <v7.88.0 that could cause HSTS functionality fail when multiple URLs are requested serially. Using its HSTS support, curl can be instructed to use HTTPS instead of usingan insecure clear-text HTTP step even when HTTP is provided in the URL. ThisHSTS mechanism would however surprisingly be ignored by subsequent transferswhen done on the same command line because the state would not be properlycarried on. (CVE-2023-23914)

- A cleartext transmission of sensitive information vulnerability exists in curl <v7.88.0 that could cause HSTS functionality to behave incorrectly when multiple URLs are requested in parallel. Using its HSTS support, curl can be instructed to use HTTPS instead of using an insecure clear-text HTTP step even when HTTP is provided in the URL. This HSTS mechanism would however surprisingly fail when multiple transfers are done in parallel as the HSTS cache file gets overwritten by the most recentlycompleted transfer. A later HTTP-only transfer to the earlier host name would then *not* get upgraded properly to HSTS.
(CVE-2023-23915)

- An allocation of resources without limits or throttling vulnerability exists in curl <v7.88.0 based on the chained HTTP compression algorithms, meaning that a server response can be compressed multiple times and potentially with differentalgorithms. The number of acceptable links in this decompression chain wascapped, but the cap was implemented on a per-header basis allowing a maliciousserver to insert a virtually unlimited number of compression steps simply byusing many headers. The use of such a decompression chain could result in a malloc bomb, making curl end up spending enormous amounts of allocated heap memory, or trying to and returning out of memory errors. (CVE-2023-23916)

- A vulnerability in input validation exists in curl <8.0 during communication using the TELNET protocol may allow an attacker to pass on maliciously crafted user name and telnet options during server negotiation.
The lack of proper input scrubbing allows an attacker to send content or perform option negotiation without the application's intent. This vulnerability could be exploited if an application allows user input, thereby enabling attackers to execute arbitrary code on the system. (CVE-2023-27533)

- A path traversal vulnerability exists in curl <8.0.0 SFTP implementation causes the tilde (~) character to be wrongly replaced when used as a prefix in the first path element, in addition to its intended use as the first element to indicate a path relative to the user's home directory. Attackers can exploit this flaw to bypass filtering or execute arbitrary code by crafting a path like /~2/foo while accessing a server with a specific user. (CVE-2023-27534)

- An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers. Previously created connections are kept in a connection pool for reuse if they match the current setup. However, certain FTP settings such as CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC, and CURLOPT_USE_SSL were not included in the configuration match checks, causing them to match too easily. This could lead to libcurl using the wrong credentials when performing a transfer, potentially allowing unauthorized access to sensitive information. (CVE-2023-27535)

- An authentication bypass vulnerability exists libcurl <8.0.0 in the connection reuse feature which can reuse previously established connections with incorrect user permissions due to a failure to check for changes in the CURLOPT_GSSAPI_DELEGATION option. This vulnerability affects krb5/kerberos/negotiate/GSSAPI transfers and could potentially result in unauthorized access to sensitive information. The safest option is to not reuse connections if the CURLOPT_GSSAPI_DELEGATION option has been changed. (CVE-2023-27536)

- A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data between separate handles.
This sharing was introduced without considerations for do this sharing across separate threads but there was no indication of this fact in the documentation. Due to missing mutexes or thread locks, two threads sharing the same HSTS data could end up doing a double-free or use-after-free. (CVE-2023-27537)

- An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection. (CVE-2023-27538)

- A use after free vulnerability exists in curl <v8.1.0 in the way libcurl offers a feature to verify an SSH server's public key using a SHA 256 hash. When this check fails, libcurl would free the memory for the fingerprint before it returns an error message containing the (now freed) hash. This flaw risks inserting sensitive heap-based data into the error message that might be shown to users or otherwise get leaked and revealed. (CVE-2023-28319)

- A denial of service vulnerability exists in curl <v8.1.0 in the way libcurl provides several different backends for resolving host names, selected at build time. If it is built to use the synchronous resolver, it allows name resolves to time-out slow operations using `alarm()` and `siglongjmp()`. When doing this, libcurl used a global buffer that was not mutex protected and a multi-threaded application might therefore crash or otherwise misbehave. (CVE-2023-28320)

- An improper certificate validation vulnerability exists in curl <v8.1.0 in the way it supports matching of wildcard patterns when listed as Subject Alternative Name in TLS server certificates. curl can be built to use its own name matching function for TLS rather than one provided by a TLS library. This private wildcard matching function would match IDN (International Domain Name) hosts incorrectly and could as a result accept patterns that otherwise should mismatch. IDN hostnames are converted to puny code before used for certificate checks. Puny coded names always start with `xn--` and should not be allowed to pattern match, but the wildcard check in curl could still check for `x*`, which would match even though the IDN name most likely contained nothing even resembling an `x`. (CVE-2023-28321)

- An information disclosure vulnerability exists in curl <v8.1.0 when doing HTTP(S) transfers, libcurl might erroneously use the read callback (`CURLOPT_READFUNCTION`) to ask for data to send, even when the `CURLOPT_POSTFIELDS` option has been set, if the same handle previously wasused to issue a `PUT` request which used that callback. This flaw may surprise the application and cause it to misbehave and either send off the wrong data or use memory after free or similar in the second transfer. The problem exists in the logic for a reused handle when it is (expected to be) changed from a PUT to a POST. (CVE-2023-28322)

- When curl retrieves an HTTP response, it stores the incoming headers so that they can be accessed later via the libcurl headers API. However, curl did not have a limit in how many or how large headers it would accept in a response, allowing a malicious server to stream an endless series of headers and eventually cause curl to run out of heap memory. (CVE-2023-38039)

- CVE-2023-38545 is a heap-based buffer overflow vulnerability in the SOCKS5 proxy handshake in libcurl and curl. When curl is given a hostname to pass along to a SOCKS5 proxy that is greater than 255 bytes in length, it will switch to local name resolution in order to resolve the address before passing it on to the SOCKS5 proxy. However, due to a bug introduced in 2020, this local name resolution could fail due to a slow SOCKS5 handshake, causing curl to pass on the hostname greater than 255 bytes in length into the target buffer, leading to a heap overflow. The advisory for CVE-2023-38545 gives an example exploitation scenario of a malicious HTTPS server redirecting to a specially crafted URL. While it might seem that an attacker would need to influence the slowness of the SOCKS5 handshake, the advisory states that server latency is likely slow enough to trigger this bug. (CVE-2023-38545)

- Please review the referenced CVE identifiers for details. Note that the risk of remote code execution is limited to SOCKS usage. (CVE-2023-38546)

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

Solution

All curl users should upgrade to the latest version:

# emerge --sync # emerge --ask --oneshot --verbose >=net-misc/curl-8.3.0-r2

Plugin Details

Severity: Critical

ID: 182879

File Name: gentoo_GLSA-202310-12.nasl

Version: 1.6

Type: local

Family: Gentoo Local Security Checks

Published: 10/11/2023

Updated: 12/8/2023

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.4

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2023-38545

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.8

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:gentoo:linux, p-cpe:/a:gentoo:linux:curl

Required KB Items: Host/local_checks_enabled, Host/Gentoo/release, Host/Gentoo/qpkg-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 10/11/2023

Vulnerability Publication Date: 12/21/2022

Reference Information

CVE: CVE-2022-43551, CVE-2022-43552, CVE-2023-23914, CVE-2023-23915, CVE-2023-23916, CVE-2023-27533, CVE-2023-27534, CVE-2023-27535, CVE-2023-27536, CVE-2023-27537, CVE-2023-27538, CVE-2023-28319, CVE-2023-28320, CVE-2023-28321, CVE-2023-28322, CVE-2023-38039, CVE-2023-38545, CVE-2023-38546

IAVA: 2023-A-0531-S

Detections

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