{"id":"CVE-2026-73261","title":"Mongoose is an embedded web server and network library","summary":"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 byte…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-20","CWE-125"],"published":"2026-10-14","updated":"2026-10-14","sourceUpdated":"2026-10-14T19:17:19.990","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-73261","references":[{"url":"https://github.com/cesanta/mongoose/commit/cc7c6d2d18c28fcc6d085633dddd88402946140a","label":"security-advisories@github.com"},{"url":"https://github.com/cesanta/mongoose/releases/tag/7.23","label":"security-advisories@github.com"},{"url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-3fmr-92g4-wchx","label":"security-advisories@github.com"}],"tags":["nvd"],"ingestedAt":"2026-10-14T19:49:57.615Z","slug":"CVE-2026-73261","body":"## Overview\n\nMongoose 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}