{"id":"CVE-2026-73261","revision":"54269a19bd9c4367b8dce2ea8c2af87e","records":[{"revision":"54269a19bd9c4367b8dce2ea8c2af87e","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-73261","aliases":[],"title":"Mongoose: handle_opt() missing opts[1] > len check — 1-byte OOB read corrupts TCP MSS, silences mg_send() per connection","description":"Mongoose is an embedded web server and network library. Prior to 7.23, the built-in TCP/IP stack enabled by MG_ENABLE_TCPIP in src/net_builtin.c does not reject a TCP option whose declared opts[1] length exceeds the remaining option bytes. In handle_opt(), a NOP followed by a truncated MSS option causes opts[3] to be read outside the declared options area and used as the low byte of dmss. An unauthenticated remote peer can corrupt the per-connection MSS value so later mg_send() calls transmit truncated or zero-length application payloads while the TCP connection otherwise appears healthy. This issue is fixed in version 7.23.","state":0,"publishedAt":"2026-10-14T18:25:41.102+00:00","modifiedAt":"2026-10-14T18:25:41.102+00:00","affected":[{"ecosystem":"Vendor product","name":"mongoose","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"cesanta\",\n                    \"product\": \"mongoose\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 7.23\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://github.com/cesanta/mongoose/security/advisories/GHSA-3fmr-92g4-wchx","https://github.com/cesanta/mongoose/commit/cc7c6d2d18c28fcc6d085633dddd88402946140a","https://github.com/cesanta/mongoose/releases/tag/7.23"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-73261","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-73261","identifiers":["CVE-2026-73261"]},"retained":false,"historicalAffected":[]}],"coverage":[]}