CVE-2026-73251

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/tlsbuiltin.c, the mgtlsinit() function stores the bundle in tls->cabundleder while tls->cader.len remains zero, and mgtlsrecvcert() uses tlsbundlefind() to accept a Common Name match without calling mgtlsverifycert_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.