{"id":"CVE-2026-73257","summary":"Mongoose: Content-Length + Transfer-Encoding coexistence enables request smuggling","details":"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.","aliases":["GHSA-5wfq-r6mr-wqp6"],"modified":"2026-08-21T11:30:30.394828498Z","published":"2026-08-20T17:30:58.424Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73257.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-444"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73257.json"},{"type":"FIX","url":"https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71"},{"type":"FIX","url":"https://github.com/cesanta/mongoose/pull/3611"},{"type":"WEB","url":"https://github.com/cesanta/mongoose/releases/tag/7.22"},{"type":"ADVISORY","url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-5wfq-r6mr-wqp6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73257"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/cesanta/mongoose","events":[{"introduced":"0"},{"fixed":"beb73a65a99619ff349c59037ea5197f27c7e533"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"0"},{"fixed":"7.22"}]}}],"versions":["7.21","7.20","7.19","7.18","7.17","7.16","7.15","7.14","7.13","7.12","7.11","7.8","7.7","7.6","7.5","7.4","7.3","7.2","7.1","7.0","6.18","6.17","6.16","6.15","6.14","6.13","6.12","6.11","6.10","6.9","6.7","6.6","6.5","6.4","6.3","6.2","6.1","6.0","5.6","5.5_20140120","5.5","5.4","5.3","5.2","5.1","5.0","4.1","4.0","3.8","3.7","3.6","3.5","3.4","3.3","3.2"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-73257.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"}]}