CVE-2022-24801 is a high-severity (CVSS 8.1) CWE-444 vulnerability in twisted. A fix is available for twisted — see the affected versions and patch details below.
HTTP Request Smuggling in twisted.web
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2022-24801.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2022-24801 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
twistedReal-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
The Twisted Web HTTP 1.1 server, located in the twisted.web.http module, parsed several HTTP request constructs more leniently than permitted by RFC 7230:
- The Content-Length header value could have a
+or-prefix. - Illegal characters were permitted in chunked extensions, such as the LF (
\n) character. - Chunk lengths, which are expressed in hexadecimal format, could have a prefix of
0x. - HTTP headers were stripped of all leading and trailing ASCII whitespace, rather than only space and HTAB (
\t).
This non-conformant parsing can lead to desync if requests pass through multiple HTTP parsers, potentially resulting in HTTP request smuggling.
Impact
You may be affected if:
- You use Twisted Web's HTTP 1.1 server and/or proxy
- You also pass requests through a different HTTP server and/or proxy
The specifics of the other HTTP parser matter. The original report notes that some versions of Apache Traffic Server and HAProxy have been vulnerable in the past. HTTP request smuggling may be a serious concern if you use a proxy to perform request validation or access control.
The Twisted Web client is not affected. The HTTP 2.0 server uses a different parser, so it is not affected.
Patches
The issue has been addressed in Twisted 22.4.0rc1 and later.
Workarounds
Other than upgrading Twisted, you could:
- Ensure any vulnerabilities in upstream proxies have been addressed, such as by upgrading them
- Filter malformed requests by other means, such as configuration of an upstream proxy
Credits
This issue was initially reported by Zhang Zeyu.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | twisted | all versions | 22.4.0pip install --upgrade 'twisted==22.4.0' |
Detection & mitigation playbook
Open-source dependencyDetect
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 22.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-24801 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2022-24801 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2022-24801. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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 Hat Enterprise Linux 6 was affected but Out of Support Cycle because python-twisted was not listed in Red Hat Enterprise Linux 6 ELS Inclusion List. https://access.redhat.com/articles/4997301
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 7 | python-twisted-web-0:12.1.0-8.el7_9 | RHSA-2022:4930 |
| Red Hat OpenStack Platform 16.1 | python-twisted-0:16.4.1-20.el8ost | RHSA-2022:1646 |
| Red Hat OpenStack Platform 16.2 | python-twisted-0:16.4.1-20.el8ost | RHSA-2022:1645 |
Frequently Asked Questions
Is CVE-2022-24801 in your dependencies?
O3 Security finds CVE-2022-24801 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.