python-hyper/h2 · Security
h2 allows HTTP Request Smuggling due to illegal characters in headers
- GHSA ID
- GHSA-847f-9342-265h
- CVE ID
- CVE-2025-57804
- Severity
- medium
- Published
- Updated
- CVSS v4
- 6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
Description
Summary
HTTP/2 request splitting vulnerability allows attackers to perform request smuggling attacks by injecting CRLF characters into headers. This occurs when servers downgrade HTTP/2 requests to HTTP/1.1 without properly validating header names/values, enabling attackers to manipulate request boundaries and bypass security controls.
CWEs
- CWE-93 · Improper Neutralization of CRLF Sequences ('CRLF Injection')
References
- https://github.com/python-hyper/h2/security/advisories/GHSA-847f-9342-265h ↗
- https://github.com/python-hyper/h2/commit/035e9899f95e3709af098f578bfc3cd302298e3a ↗
- https://nvd.nist.gov/vuln/detail/CVE-2025-57804 ↗
- https://lists.debian.org/debian-lts-announce/2025/09/msg00004.html ↗
- https://github.com/advisories/GHSA-847f-9342-265h ↗