How severe is CVE-2022-21716?

CVE-2022-21716 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2022-21716?

CVE-2022-21716 affects the following packages: twisted (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2022-21716?

Update twisted to 22.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-21716 is resolved across your whole dependency graph.

How do I detect CVE-2022-21716 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for twisted, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2022-21716 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2022-21716 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2022-21716, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2022-21716?

CVE-2022-21716 has an EPSS (Exploit Prediction Scoring System) score of 3.5%, placing it in the 89th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2022-21716?

CVE-2022-21716 is classified as CWE-120 (CWE-120), CWE-770 (CWE-770). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2022-21716 published, and has it been updated?

CVE-2022-21716 was published on March 3, 2022 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

HIGH severity

CVE-2022-21716 — twisted

HIGHFix: twisted/twisted@89c395e

CVE-2022-21716 is a high-severity (CVSS 7.5) CWE-120 vulnerability in twisted. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for twisted — see the affected versions and patch details below.

Buffer Overflow in Twisted

Also known asGHSA-rv6r-3f5q-9rgxPYSEC-2022-160

Published

Mar 3, 2022

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for CVE-2022-21716.

EPSS Exploitation Probability

via FIRST.org ↗

3.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs89th percentile — riskier than 89% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐍twisted

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

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 Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`twisted`	≥ 21.7.0&&< 22.2.0	22.2.0`pip install --upgrade 'twisted==22.2.0'`

Affected Products

5 products · 7 configurations

debian linuxdebian

1 version

9.0

fedorafedoraproject

2 versions

3536

Application

http serveroracle

2 versions

12.2.1.3.012.2.1.4.0

Application

zfs storage appliance kitoracle

1 version

8.8

Application

twistedtwisted

≥ 21.7.0 && < 22.2.0

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Twisted is an event-based framework for internet applications, supportin…

github.comNVDMar 2022

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for twisted, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update twisted to 22.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-21716 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

Product	Fixed in	Advisory
Red Hat OpenStack Platform 16.1	`python-twisted-0:16.4.1-19.el8ost`	RHSA-2022:0982
Red Hat OpenStack Platform 16.2	`python-twisted-0:16.4.1-19.el8ost`	RHSA-2022:0992

Frequently Asked Questions

### 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. *

O3 Security · Impact-Aware SCA

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