{"id":"CVE-2025-57804","summary":"h2 allows HTTP Request Smuggling due to illegal characters in headers","details":"h2 is a pure-Python implementation of a HTTP/2 protocol stack. Prior to version 4.3.0, an 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. This issue has been patched in version 4.3.0.","aliases":["GHSA-847f-9342-265h"],"modified":"2026-04-10T05:32:40.793976Z","published":"2025-08-25T21:04:52.642Z","related":["CGA-7g62-rj7g-p7c6","SUSE-SU-2025:03199-1","SUSE-SU-2025:03273-1","SUSE-SU-2026:20187-1","openSUSE-SU-2025:15496-1","openSUSE-SU-2026:20122-1"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-93"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/57xxx/CVE-2025-57804.json"},"references":[{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/09/msg00004.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/57xxx/CVE-2025-57804.json"},{"type":"ADVISORY","url":"https://github.com/python-hyper/h2/security/advisories/GHSA-847f-9342-265h"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-57804"},{"type":"FIX","url":"https://github.com/python-hyper/h2/commit/035e9899f95e3709af098f578bfc3cd302298e3a"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/python-hyper/h2","events":[{"introduced":"0"},{"fixed":"1aae569315eb170cdff00582644aca37ee38db62"}]}],"versions":["v1.0.0","v1.1.0","v1.1.1","v2.0.0","v2.1.0","v2.2.0","v2.3.0","v2.4.0","v2.5.0","v2.6.0","v3.0.0","v3.1.0","v3.1.1","v3.2.0","v4.0.0","v4.1.0","v4.2.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-57804.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"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"}]}