USN-7108-1: AsyncSSH vulnerabilities

Releases

• Ubuntu 24.04 LTS
• Ubuntu 22.04 LTS
• Ubuntu 20.04 LTS

Packages

• python-asyncssh - asyncio-based client and server implementation of SSHv2 protocol

Details

Fabian Bäumer, Marcus Brinkmann, and Jörg Schwenk discovered that AsyncSSH
did not properly handle the extension info message. An attacker able to
intercept communications could possibly use this issue to downgrade
the algorithm used for client authentication. (CVE-2023-46445)

Fabian Bäumer, Marcus Brinkmann, and Jörg Schwenk discovered that AsyncSSH
did not properly handle the user authentication request message. An
attacker could possibly use this issue to control the remote end of an SSH
client session via packet injection/removal and shell emulation.
(CVE-2023-46446)

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 24.04

• python3-asyncssh - 2.10.1-2ubuntu0.1+esm1
  Available with Ubuntu Pro

Ubuntu 22.04

• python3-asyncssh - 2.5.0-1ubuntu0.1

Ubuntu 20.04

• python3-asyncssh - 1.12.2-1ubuntu0.2

In general, a standard system update will make all the necessary changes.

References

• CVE-2023-46445
• CVE-2023-46446