GHSA-rv6r-3f5q-9rgxHighCVSS 7.5

Twisted SSH client and server deny of service during SSH handshake.

Published
March 3, 2022
Last Modified
November 25, 2024

🔗 CVE IDs covered (1)

CVE-2022-21716 →

📋 Description

Impact

The Twisted SSH client and server implementation naively accepted an infinite amount of data for the peer's SSH version identifier.

A malicious peer can trivially craft a request that uses all available memory and crash the server, resulting in denial of service. The attack is as simple as nc -rv localhost 22 < /dev/zero.

Patches

The issue was fix in GitHub commit https://github.com/twisted/twisted/commit/98387b39e9f0b21462f6abc7a1325dc370fcdeb1

A fix is available in Twisted 22.2.0.

Workarounds

  • Limit access to the SSH server only to trusted source IP addresses.
  • Connect over SSH only to trusted destination IP addresses.

References

Reported at https://twistedmatrix.com/trac/ticket/10284 Discussions at https://github.com/twisted/twisted/security/advisories/GHSA-rv6r-3f5q-9rgx

For more information

Found by vin01

🎯 Affected products1

  • pip/twisted:>= 21.7.0, < 22.2.0

🔗 References (15)