CVE-2023-46445: AsyncSSH Rogue Extension Negotiation
Summary
CVE-2023-46445: AsyncSSH Rogue Extension Negotiation. Affects asyncssh versions < 2.14.1. Fixed in 2.14.1. How to fix ↓
Also tracked for
- python-asyncssh · Debian:11
The same CVE-2023-46445 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
AsyncSSH is an open-source Python library that provides an asynchronous SSH client and server implementation. It allows users to establish secure connections and perform various SSH operations. However, versions up to 2.14.0 are vulnerable to a rogue extension negotiation attack.
Vulnerability Detail
The rogue extension negotiation attack in AsyncSSH allows an attacker to control the extension info message sent by the SSH server during the connection establishment process. By exploiting an implementation flaw in AsyncSSH, the attacker can inject a chosen extension info message and replace the original one. This attack can lead to algorithm downgrade during user authentication, potentially weakening the security of the SSH connection.
How To Fix
Latest published version: 2.24.1 as of 23 Oct 2026
pip install --upgrade "asyncssh==2.24.1"Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
2.14.1
This is the first release that contains the fix.
pip install --upgrade "asyncssh==2.14.1"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
There is no known workaround for this vulnerability. It is recommended to upgrade to the fixed version of AsyncSSH as soon as possible.
Conclusion
The rogue extension negotiation vulnerability in AsyncSSH can be mitigated by upgrading to version 2.14.1 or later. It is recommended to update the AsyncSSH installation as soon as possible to ensure the security of SSH connections. For further support on vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for asyncssh →
FAQ
AsyncSSH is a Python library that provides an asynchronous SSH client and server implementation.
The vulnerability allows an attacker to control the extension info message sent by the SSH server, potentially leading to algorithm downgrade during user authentication.
You can fix this vulnerability by upgrading to AsyncSSH version 2.14.1 or later.
No, there is no known workaround for this vulnerability.
You can find more information about this vulnerability in the official GitHub advisory: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2023/11/GHSA-cfc2-wr2v-gxm5/GHSA-cfc2-wr2v-gxm5.json
References
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