CVE-2026-73253 — Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching
Mongoose is an embedded web server and network library. Prior to version 7.22, an on-path network attacker with a wildcard certificate for a parent domain can impersonate deeper…
Published: 2026-08-20 · CVSS: 9.1 · CVSS 4.0
Mongoose is an embedded web server and network library. Prior to version 7.22, an on-path network attacker with a wildcard certificate for a parent domain can impersonate deeper subdomains to a client using the built-in TLS stack. The mg_tls_verify_cert_san() and mg_tls_verify_cert_cn() functions in src/tls_builtin.c call mg_match(), whose wildcard can cross DNS label boundaries, so a pattern such as *.example.com can match foo.bar.example.com. The resulting hostname verification bypass permits interception and modification of TLS traffic. This issue is fixed in version 7.22.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7