Improper Certificate Validation Affecting mongoose package, versions <7.22+ds-1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIANUNSTABLE-MONGOOSE-19186421
- published22 Aug 2026
- disclosed20 Aug 2026
Introduced: 20 Aug 2026
NewCVE-2026-73253 (opens in a new tab)How to fix?
Upgrade Debian:unstable mongoose to version 7.22+ds-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream mongoose package and not the mongoose package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
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.
References
- https://security-tracker.debian.org/tracker/CVE-2026-73253
- https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71
- https://github.com/cesanta/mongoose/pull/3611
- https://github.com/cesanta/mongoose/releases/tag/7.22
- https://github.com/cesanta/mongoose/security/advisories/GHSA-jp6g-796f-39vp