CVE-2025-43859
h11 is a Python implementation of HTTP/1.1. Prior to version 0.16.0, a leniency in h11's parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions. This issue has been patched in version 0.16.0. Since exploitation requires the combination of buggy h11 with a buggy (reverse) proxy, fixing either component is sufficient to mitigate this issue.
- Score
- CVSS 3.1 9.1 Critical
- Status
- Deferred - security-advisories@github.com
- Published
- 2025-04-24
- Last modified
- 2025-04-24
- Weaknesses
- CWE-444
Affected products
References
- https://github.com/python-hyper/h11/commit/114803a29ce50116dc47951c690ad4892b1a36ed
- https://github.com/python-hyper/h11/security/advisories/GHSA-vqfr-h8mv-ghfj
