{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-73256", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-08-11T17:18:01.598Z", "datePublished": "2026-08-20T17:37:54.505Z", "dateUpdated": "2026-08-20T17:37:54.505Z"}, "containers": {"cna": {"title": "Mongoose: HTTP/1.0 detection off-by-one enables request smuggling via chunked TE", "problemTypes": [{"descriptions": [{"cweId": "CWE-444", "lang": "en", "description": "CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')", "type": "CWE"}]}], "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"}}], "references": [{"name": "https://github.com/cesanta/mongoose/security/advisories/GHSA-mgp5-rjrv-h5j3", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/cesanta/mongoose/security/advisories/GHSA-mgp5-rjrv-h5j3"}, {"name": "https://github.com/cesanta/mongoose/pull/3611", "tags": ["x_refsource_MISC"], "url": "https://github.com/cesanta/mongoose/pull/3611"}, {"name": "https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71", "tags": ["x_refsource_MISC"], "url": "https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71"}, {"name": "https://github.com/cesanta/mongoose/releases/tag/7.22", "tags": ["x_refsource_MISC"], "url": "https://github.com/cesanta/mongoose/releases/tag/7.22"}], "affected": [{"vendor": "cesanta", "product": "mongoose", "versions": [{"version": "< 7.22", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-08-20T17:37:54.505Z"}, "descriptions": [{"lang": "en", "value": "Mongoose is an embedded web server and network library. Prior to 7.22, a remote unauthenticated attacker can exploit an HTTP/1.0 reverse-proxy deployment by sending a request with Transfer-Encoding: chunked and conflicting framing. The http_cb() function in src/http.c tests hm.proto.len with an impossible greater-than-eight condition even though mg_http_parse() requires an eight-byte protocol string, so is_http_1_0 is never set. Mongoose consequently processes chunked encoding that an HTTP/1.0 proxy can ignore, enabling request smuggling and unauthorized access or state changes. This issue is fixed in version 7.22."}], "source": {"advisory": "GHSA-mgp5-rjrv-h5j3", "discovery": "UNKNOWN"}}}}

{}

{"affected": [{"affectedData": [{"product": "mongoose", "vendor": "cesanta", "versions": [{"status": "affected", "version": "< 7.22"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Mongoose is an embedded web server and network library. Prior to 7.22, a remote unauthenticated attacker can exploit an HTTP/1.0 reverse-proxy deployment by sending a request with Transfer-Encoding: chunked and conflicting framing. The http_cb() function in src/http.c tests hm.proto.len with an impossible greater-than-eight condition even though mg_http_parse() requires an eight-byte protocol string, so is_http_1_0 is never set. Mongoose consequently processes chunked encoding that an HTTP/1.0 proxy can ignore, enabling request smuggling and unauthorized access or state changes. This issue is fixed in version 7.22."}], "id": "CVE-2026-73256", "lastModified": "2026-08-20T18:16:46.523", "metrics": {"cvssMetricV31": [{"cvssData": {"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"}, "exploitabilityScore": 3.9, "impactScore": 5.2, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-08-20T18:16:46.523", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71"}, {"source": "security-advisories@github.com", "url": "https://github.com/cesanta/mongoose/pull/3611"}, {"source": "security-advisories@github.com", "url": "https://github.com/cesanta/mongoose/releases/tag/7.22"}, {"source": "security-advisories@github.com", "url": "https://github.com/cesanta/mongoose/security/advisories/GHSA-mgp5-rjrv-h5j3"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-444"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,7.22)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "mongoose", "source": "cna", "vendor": "cesanta"}, "product": "mongoose", "vendor": "cesanta"}], "created": "2026-08-20T18:30:03.740623+00:00", "updated": "2026-08-20T19:45:03.896374+00:00", "vendors": ["cesanta", "cesanta$PRODUCT$mongoose"]}