{"id":"CVE-2025-43859","summary":"h11 accepts some malformed Chunked-Encoding bodies","details":"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.","aliases":["GHSA-vqfr-h8mv-ghfj"],"modified":"2026-04-10T05:27:07.794325Z","published":"2025-04-24T18:15:53.328Z","related":["CGA-6c4f-hqr7-3vw2","SUSE-SU-2025:1430-1","SUSE-SU-2025:20330-1","SUSE-SU-2025:20331-1","openSUSE-SU-2025:15032-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/43xxx/CVE-2025-43859.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-444"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/43xxx/CVE-2025-43859.json"},{"type":"ADVISORY","url":"https://github.com/python-hyper/h11/security/advisories/GHSA-vqfr-h8mv-ghfj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-43859"},{"type":"FIX","url":"https://github.com/python-hyper/h11/commit/114803a29ce50116dc47951c690ad4892b1a36ed"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/python-hyper/h11","events":[{"introduced":"0"},{"fixed":"1c5b07581f058886c8bdd87adababd7d959dc7ca"}]}],"versions":["v0.11.0","v0.12.0","v0.13.0","v0.14.0","v0.15.0","v0.5.0","v0.6.0","v0.7.0","v0.8.0","v0.9.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-43859.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"}]}