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
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
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' |
Affected Products
debian linuxdebianfedorafedoraprojectzfs storage appliance kitoracletwistedtwistedDetection & 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
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
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
Filter malformed requests like '+ or -' in Content-Length header, Illegal characters like LF(\n) and HTAB(\t), and 0x prefixes in HTTP Headers.Source: Red Hat security advisory for CVE-2022-24801 (CC BY 4.0)
| 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?
Find it across PyPI, including transitive dependencies.