{"id":"CVE-2026-73261","published":"2026-10-14T19:17:19.990","lastModified":"2026-10-16T20:04:29.760","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.","cvssScore":7.5,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwes":["CWE-20","CWE-125"],"vendors":[],"products":[],"references":[{"url":"https://github.com/cesanta/mongoose/commit/cc7c6d2d18c28fcc6d085633dddd88402946140a","tags":[]},{"url":"https://github.com/cesanta/mongoose/releases/tag/7.23","tags":[]},{"url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-3fmr-92g4-wchx","tags":[]}],"exploitRefs":[{"url":"https://github.com/cesanta/mongoose/commit/cc7c6d2d18c28fcc6d085633dddd88402946140a","tags":[]},{"url":"https://github.com/cesanta/mongoose/releases/tag/7.23","tags":[]},{"url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-3fmr-92g4-wchx","tags":[]}],"hasPoc":true,"ai":null}