{"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":9.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","cwe":["CWE-295"],"vendor":"cesanta","product":"mongoose","affected":["mongoose < 7.23"],"patched":["mongoose 7.23"],"published":"2026-08-20","updated":"2026-09-29","sourceUpdated":"2026-09-29T15:38:03.243","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"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-73251.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-73251"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-73251"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00193,"epssPercentile":0.08855,"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-08-20T19:50:25.364486Z"},"scores":{"nvd":9.1,"cna":9.3,"vendor":7.4},"ingestedAt":"2026-09-14T15:23:34.738Z","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## Affected\n\n- `mongoose < 7.23`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `mongoose 7.23`\n\n## Vendor advisories\n\n- **Red Hat VEX** · updated 2026-09-29 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-73251.json)","depth":"midnight","depthScore":50,"depthScoreParts":{"impact":50.1,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":212736,"id":"CVE-2026-73251","ts":1790700012290,"field":"cvss","old":"9.3","new":"9.1"}]}