{"id":"CVE-2026-73251","aliases":["GHSA-qj6j-2692-v2r8"],"url":"https://o3.security/vulnerability/CVE-2026-73251","summary":"Mongoose Built-in TLS: CA-bundle certificate chain accepted without any signature verification","details":"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 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.","published":"2026-08-20T17:34:50.472Z","modified":"2026-08-22T03:58:10.344603071Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":{"url":"https://github.com/cesanta/mongoose/commit/2988bc9df3a5efc9539471cb7455975fa25df483","label":"cesanta/mongoose@2988bc9"},"references":[{"type":"WEB","url":"https://github.com/cesanta/mongoose/releases/tag/7.23"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73251.json"},{"type":"ADVISORY","url":"https://github.com/cesanta/mongoose/security/advisories/GHSA-qj6j-2692-v2r8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73251"},{"type":"FIX","url":"https://github.com/cesanta/mongoose/commit/2988bc9df3a5efc9539471cb7455975fa25df483"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-22T03:58:10.344603071Z"}}