{"id":"CVE-2026-73251","title":"Mongoose is an embedded web server and network library","summary":"Mongoose is an embedded web server and network library. Prior to 7.23, a network attacker can impersonate a TLS server to a Mongoose client configured with a multi-certificate CA bundle. In src/tls_builtin.c, the mg_tls_init() function s…","severity":"critical","cvss":9.3,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","cwe":["CWE-295"],"vendor":"cesanta","product":"mongoose","affected":["mongoose < 7.23"],"published":"2026-08-20","updated":"2026-09-09","sourceUpdated":"2026-09-09T21:19:49.197","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-73251","references":[{"url":"https://github.com/cesanta/mongoose/commit/2988bc9df3a5efc9539471cb7455975fa25df483","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-qj6j-2692-v2r8","label":"security-advisories@github.com"},{"url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-qj6j-2692-v2r8","label":"security-advisories@github.com"},{"url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-qj6j-2692-v2r8","label":"security-advisories@github.com"},{"url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-qj6j-2692-v2r8","label":"security-advisories@github.com"}],"tags":["nvd","cve.org"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-08-20T19:50:25.364486Z"},"cvssSource":"cna","ingestedAt":"2026-09-14T15:23:34.738Z","epss":0.00195,"epssPercentile":0.09541,"slug":"CVE-2026-73251","body":"## Overview\n\nMongoose is an embedded web server and network library. Prior to 7.23, a network attacker can impersonate a TLS server to a Mongoose client configured with a multi-certificate CA bundle. In src/tls_builtin.c, the mg_tls_init() function stores the bundle in tls->ca_bundle_der while tls->ca_der.len remains zero, and mg_tls_recv_cert() uses tls_bundle_find() to accept a Common Name match without calling mg_tls_verify_cert_signature(). A forged self-signed certificate can therefore satisfy hostname and CertificateVerify checks and enable interception, credential disclosure, traffic modification, and malicious responses. 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":"midnight","depthScore":51,"depthScoreParts":{"impact":51.2,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}