Arch Linux Security Advisory ASA-202107-63
==========================================

Severity: Medium
Date    : 2021-07-21
CVE-ID  : CVE-2021-22924 CVE-2021-22925
Package : libcurl-gnutls
Type    : multiple issues
Remote  : Yes
Link    : https://security.archlinux.org/AVG-2198

Summary
=======

The package libcurl-gnutls before version 7.78.0-1 is vulnerable to
multiple issues including information disclosure and insufficient
validation.

Resolution
==========

Upgrade to 7.78.0-1.

# pacman -Syu "libcurl-gnutls>=7.78.0-1"

The problems have been fixed upstream in version 7.78.0.

Workaround
==========

CVE-2021-22925 can be mitigated by avoiding to use
CURLOPT_TELNETOPTIONS. No known workaround exists for CVE-2021-22924.

Description
===========

- CVE-2021-22924 (insufficient validation)

A security issue has been found in curl before version 7.78.0. libcurl
keeps previously used connections in a connection pool for subsequent
transfers to reuse, if one of them matches the setup. Due to errors in
the logic, the config matching function did not take 'issuer cert' into
account and it compared the involved paths case insensitively, which
could lead to libcurl reusing wrong connections. File paths are, or can
be, case sensitive on many systems but not all, and can even vary
depending on used file systems. The comparison also didn't include the
'issuer cert' which a transfer can set to qualify how to verify the
server certificate.

- CVE-2021-22925 (information disclosure)

A security issue has been found in curl before version 7.78.0. curl
supports the -t command line option, known as CURLOPT_TELNETOPTIONS in
libcurl. This rarely used option is used to send variable=content pairs
to TELNET servers. Due to flaw in the option parser for sending NEW_ENV
variables, libcurl before version 7.78.0 could be made to pass on
uninitialized data from a stack based buffer to the server. Therefore
potentially revealing sensitive internal information to the server
using a clear-text network protocol. This could happen because curl did
not call and use sscanf() correctly when parsing the string provided by
the application.

The previous curl security vulnerability CVE-2021-22898 is almost
identical to this one but the fix was insufficient so this security
vulnerability remained.

Impact
======

libcurl could disclose potentially sensitive memory contents to a
remote server when an uncommon option for TELNET servers is used.
Additionally, libcurl did not sufficiently verify the 'issuer cert'
when reusing connections.

References
==========

https://curl.se/docs/CVE-2021-22924.html
https://github.com/curl/curl/commit/5ea3145850ebff1dc2b13d17440300a01ca38161
https://curl.se/docs/CVE-2021-22925.html
https://github.com/curl/curl/commit/894f6ec730597eb243618d33cc84d71add8d6a8a
https://security.archlinux.org/CVE-2021-22924
https://security.archlinux.org/CVE-2021-22925