1. Ubuntu Security Notices
  2. USN-7051-1

USN-7051-1: AsyncSSH vulnerability

Publication date

2 October 2024

Overview

A protocol flaw was fixed in AsyncSSH.

Releases

Packages

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

Details

Fabian Bäumer, Marcus Brinkmann, Jörg Schwenk discovered that the SSH
protocol was vulnerable to a prefix truncation attack. If a remote attacker
was able to intercept SSH communications, extension negotiation messages
could be truncated, possibly leading to certain algorithms and features
being downgraded. This issue is known as the Terrapin attack. This update
adds protocol extensions to mitigate this issue.

Fabian Bäumer, Marcus Brinkmann, Jörg Schwenk discovered that the SSH
protocol was vulnerable to a prefix truncation attack. If a remote attacker
was able to intercept SSH communications, extension negotiation messages
could be truncated, possibly leading to certain algorithms and features
being downgraded. This issue is known as the Terrapin attack. This update
adds protocol extensions to mitigate this issue.

Update instructions

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

Learn more about how to get the fixes.

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

Ubuntu Release Package Version
24.04 noble python3-asyncssh –  2.10.1-2ubuntu0.1
22.04 jammy python3-asyncssh –  2.5.0-1ubuntu0.1~esm1  
20.04 focal python3-asyncssh –  1.12.2-1ubuntu0.1

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References

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