CVE-2026-73251
CriticalCVSS 9.3Summary
A vulnerability in Mongoose before version 7.23 allows a network attacker to impersonate a TLS server to a Mongoose client configured with a multi-certificate CA bundle. 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 verifying the certificate signature.
Risk Assessment
The risk includes interception, credential disclosure, traffic modification, and malicious responses, potentially leading to full communication compromise.
Recommendation
Upgrade Mongoose to version 7.23 or later, which includes the fix.
Original NVD description (English source)
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.