{"id":"CVE-2025-43859","state":"PUBLISHED","title":"h11 accepts some malformed Chunked-Encoding bodies","description":"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.","publishedAt":"2025-04-24T18:15:53.328Z","updatedAt":"2025-04-24T19:02:45.130Z","severity":{"score":9.1,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["python-hyper h11"],"affected":[{"vendor":"python-hyper","product":"h11","versions":[{"version":"< 0.16.0","status":"affected"}]}],"references":["https://github.com/python-hyper/h11/security/advisories/GHSA-vqfr-h8mv-ghfj","https://github.com/python-hyper/h11/commit/114803a29ce50116dc47951c690ad4892b1a36ed"],"weaknesses":["CWE-444"],"ingestedAt":"2026-10-29T20:09:17.366Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/43xxx/CVE-2025-43859.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.1","cveMetadata":{"cveId":"CVE-2025-43859","state":"PUBLISHED","datePublished":"2025-04-24T18:15:53.328Z","dateUpdated":"2025-04-24T19:02:45.130Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2025-04-17T20:07:08.556Z"},"containers":{"cna":{"title":"h11 accepts some malformed Chunked-Encoding bodies","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"python-hyper","product":"h11","versions":[{"version":"< 0.16.0","status":"affected"}]}],"references":[{"url":"https://github.com/python-hyper/h11/security/advisories/GHSA-vqfr-h8mv-ghfj","name":"https://github.com/python-hyper/h11/security/advisories/GHSA-vqfr-h8mv-ghfj","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/python-hyper/h11/commit/114803a29ce50116dc47951c690ad4892b1a36ed","name":"https://github.com/python-hyper/h11/commit/114803a29ce50116dc47951c690ad4892b1a36ed","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":9.1,"baseSeverity":"CRITICAL","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-444","lang":"en","description":"CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2025-04-24T18:15:53.328Z"},"source":{"advisory":"GHSA-vqfr-h8mv-ghfj","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2025-04-24T19:02:05.000674Z","id":"CVE-2025-43859","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-04-24T19:02:45.130Z"}}]}}}