Twisted SSH client and server deny of service during SSH handshake.
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 software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | twisted | >= 21.7.0, < 22.2.0 | 22.2.0 |
References
- https://github.com/twisted/twisted/commit/89c395ee794e85a9657b112c4351417850330ef9
- https://github.com/twisted/twisted/security/advisories/GHSA-rv6r-3f5q-9rgx
- https://twistedmatrix.com/trac/ticket/10284
- https://github.com/twisted/twisted/releases/tag/twisted-22.2.0
- https://nvd.nist.gov/vuln/detail/CVE-2022-21716
- https://github.com/twisted/twisted/commit/98387b39e9f0b21462f6abc7a1325dc370fcdeb1
- https://github.com/pypa/advisory-database/tree/main/vulns/twisted/PYSEC-2022-160.yaml
- https://github.com/twisted/twisted
- https://lists.debian.org/debian-lts-announce/2022/03/msg00009.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7U6KYDTOLPICAVSR34G2WRYLFBD2YW5K
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GLKHA6WREIVAMBQD7KKWYHPHGGNKMAG6
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/7U6KYDTOLPICAVSR34G2WRYLFBD2YW5K
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GLKHA6WREIVAMBQD7KKWYHPHGGNKMAG6
- https://security.gentoo.org/glsa/202301-02
- https://www.oracle.com/security-alerts/cpuapr2022.html
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-120, CWE-770- Platform
- Python (PyPI)
- Package
twisted- Disclosed
- 03.03.2022
- Updated
- 11.10.2026 11:20
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2022-160 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-rv6r-3f5q-9rgx - CC BY 4.0
Vulnerability history: twisted
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 17
- First → latest
- 06.2019 10.2026
- Without a fix
- 1
- Exploited in attacks
- 0
Severity breakdown
- Critical 5
- High 4
- Medium 8
Disclosures per year
- 2019: 3
- 2020: 3
- 2021: 0
- 2022: 6
- 2023: 1
- 2024: 2
- 2025: 0
- 2026: 2
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Twisted SSH client and server deny of service during SSH handshake. this entry
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