{"id":"CVE-2026-73257","state":"PUBLISHED","title":"Mongoose: Content-Length + Transfer-Encoding coexistence enables request smuggling","description":"Mongoose is an embedded web server and network library. Priro to version 7.22, a remote unauthenticated attacker can send an HTTP request containing both Content-Length and Transfer-Encoding: chunked. The cl_count and te_count checks in the mg_http_parse() and http_cb() paths in src/http.c accept both headers and prioritize chunked encoding, while a Content-Length-preferring reverse proxy can use a different request boundary. This CL.TE desynchronization can inject requests that access or modify resources in another user context. This issue is fixed in version 7.22.","publishedAt":"2026-08-20T17:30:58.424Z","updatedAt":"2026-08-20T19:34:58.840Z","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":["cesanta mongoose"],"affected":[{"vendor":"cesanta","product":"mongoose","versions":[{"version":"< 7.22","status":"affected"}]}],"references":["https://github.com/cesanta/mongoose/security/advisories/GHSA-5wfq-r6mr-wqp6","https://github.com/cesanta/mongoose/pull/3611","https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71","https://github.com/cesanta/mongoose/releases/tag/7.22"],"weaknesses":["CWE-444"],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/73xxx/CVE-2026-73257.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-73257","state":"PUBLISHED","datePublished":"2026-08-20T17:30:58.424Z","dateUpdated":"2026-08-20T19:34:58.840Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-11T17:18:01.598Z"},"containers":{"cna":{"title":"Mongoose: Content-Length + Transfer-Encoding coexistence enables request smuggling","descriptions":[{"lang":"en","value":"Mongoose is an embedded web server and network library. Priro to version 7.22, a remote unauthenticated attacker can send an HTTP request containing both Content-Length and Transfer-Encoding: chunked. The cl_count and te_count checks in the mg_http_parse() and http_cb() paths in src/http.c accept both headers and prioritize chunked encoding, while a Content-Length-preferring reverse proxy can use a different request boundary. This CL.TE desynchronization can inject requests that access or modify resources in another user context. This issue is fixed in version 7.22."}],"affected":[{"vendor":"cesanta","product":"mongoose","versions":[{"version":"< 7.22","status":"affected"}]}],"references":[{"url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-5wfq-r6mr-wqp6","name":"https://github.com/cesanta/mongoose/security/advisories/GHSA-5wfq-r6mr-wqp6","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/cesanta/mongoose/pull/3611","name":"https://github.com/cesanta/mongoose/pull/3611","tags":["x_refsource_MISC"]},{"url":"https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71","name":"https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71","tags":["x_refsource_MISC"]},{"url":"https://github.com/cesanta/mongoose/releases/tag/7.22","name":"https://github.com/cesanta/mongoose/releases/tag/7.22","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":"2026-08-20T17:30:58.424Z"},"source":{"advisory":"GHSA-5wfq-r6mr-wqp6","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-5wfq-r6mr-wqp6","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-20T19:34:52.897430Z","id":"CVE-2026-73257","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-20T19:34:58.840Z"}}]}}}