# CVE-2026-73253: mongoose: Mongoose is an embedded web server and network library

CVE-2026-73253 is fixed in mongoose on 1 platform by DEBIAN-CVE-2026-73253 (version 7.22+ds-1), released August 21, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-73253
- Priority: Urgent
- CVSS: 9.1 (critical)
- EPSS: 0.0034
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 20, 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | mongoose Debian 14 | 7.22+ds-1 | [DEBIAN-CVE-2026-73253](https://patchblox.com/security/data/fix/linux/debian-cve-2026-73253.md) | Aug 21, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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