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Ubuntu Security Notice USN-7108-2
December 12, 2024

python-asyncssh vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS

Summary:

Several issues were fixed in AsyncSSH.

Software Description:
- python-asyncssh: asyncio-based client and server implementation of SSHv2 
protocol

Details:

USN-7108-1 fixed vulnerabilities in AysncSSH. This update provides the
corresponding update for Ubuntu 18.04 LTS.

Original advisory 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 18.04 LTS
  python3-asyncssh                1.11.1-1ubuntu0.1~esm2
                                  Available with Ubuntu Pro

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

References:
  https://ubuntu.com/security/notices/USN-7108-2
  https://ubuntu.com/security/notices/USN-7108-1
  CVE-2023-46445, CVE-2023-46446