CVE-2026-73253
Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching
- State
- Published
- Severity
- 9.1 Critical
- Published
- Aug 20, 2026
- Updated
- Aug 20, 2026
- Reserved
- Aug 11, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.1 Critical | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N | GitHub_M |
Weaknesses
- CWE-295 Improper Certificate Validation
Affected Products
| Product | Versions |
|---|---|
mongoosecesanta |
|
References
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