{"id":"CVE-2025-57804","state":"PUBLISHED","title":"h2 allows HTTP Request Smuggling due to illegal characters in headers","description":"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.","publishedAt":"2025-08-25T21:04:52.642Z","updatedAt":"2025-11-03T18:13:44.839Z","severity":{"score":6.9,"label":"Medium","version":"4.0","vector":"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","source":"GitHub_M"},"assigner":"GitHub_M","products":["python-hyper h2"],"affected":[{"vendor":"python-hyper","product":"h2","versions":[{"version":"< 4.3.0","status":"affected"}]}],"references":["https://github.com/python-hyper/h2/security/advisories/GHSA-847f-9342-265h","https://github.com/python-hyper/h2/commit/035e9899f95e3709af098f578bfc3cd302298e3a","https://lists.debian.org/debian-lts-announce/2025/09/msg00004.html"],"weaknesses":["CWE-93"],"ingestedAt":"2026-10-29T20:09:39.787Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/57xxx/CVE-2025-57804.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-57804","state":"PUBLISHED","datePublished":"2025-08-25T21:04:52.642Z","dateUpdated":"2025-11-03T18:13:44.839Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2025-08-20T14:30:35.009Z"},"containers":{"cna":{"title":"h2 allows HTTP Request Smuggling due to illegal characters in headers","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"python-hyper","product":"h2","versions":[{"version":"< 4.3.0","status":"affected"}]}],"references":[{"url":"https://github.com/python-hyper/h2/security/advisories/GHSA-847f-9342-265h","name":"https://github.com/python-hyper/h2/security/advisories/GHSA-847f-9342-265h","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/python-hyper/h2/commit/035e9899f95e3709af098f578bfc3cd302298e3a","name":"https://github.com/python-hyper/h2/commit/035e9899f95e3709af098f578bfc3cd302298e3a","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"LOW","subAvailabilityImpact":"NONE","baseScore":6.9,"baseSeverity":"MEDIUM","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-93","lang":"en","description":"CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2025-08-25T21:04:52.642Z"},"source":{"advisory":"GHSA-847f-9342-265h","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2025-08-26T19:14:14.359281Z","id":"CVE-2025-57804","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-08-26T19:14:49.643Z"}},{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/09/msg00004.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-03T18:13:44.839Z"}}]}}}