Arch Linux Security Advisory ASA-202106-4

Severity: High
Date    : 2021-06-01
CVE-ID  : CVE-2021-22898 CVE-2021-22901
Package : curl
Type    : multiple issues
Remote  : Yes
Link    :


The package curl before version 7.77.0-1 is vulnerable to multiple
issues including arbitrary code execution and information disclosure.


Upgrade to 7.77.0-1.

# pacman -Syu "curl>=7.77.0-1"

The problems have been fixed upstream in version 7.77.0.


- CVE-2021-22898 can be mitigated by avoiding to use the -t command
- No known workaround exists for CVE-2021-22901.


- CVE-2021-22898 (information disclosure)

A security issue has been found in curl before version 7.77.0. 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 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

- CVE-2021-22901 (arbitrary code execution)

libcurl before version 7.77.0 can be tricked into using already freed
memory when a new TLS session is negotiated or a client certificate is
requested on an existing connection. For example, this can happen when
a TLS server requests a client certificate on a connection that was
established without one. A malicious server can use this in rare
unfortunate circumstances to potentially reach remote code execution in
the client. The flaw can only happen in libcurl built to use OpenSSL.


curl could disclose potentially sensitive memory information to a
remote server over Telnet when an uncommon option is used.
Additionally, a remote attacker could cause arbitrary code execution
through a crafted TLS handshake.