Critical 9.1Published Aug 20, 2026

CVE-2026-73253Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching

Updated under an hour ago (2026-10-19 10:10 UTC)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for cesanta mongoose

Exploited in the last 30 days

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.

CVSS: 9.1 CRITICAL (v4.0, CNA)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
Weakness (CWE): CWE-295
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Aug 20, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

cesanta mongoose cesanta:mongoose (from the name)	before 7.22	CNA record
cesanta mongoose cesanta:mongoose	before 7.22	NVD

References

https://github.com/cesanta/mongoose/security/advisories/GHSA-jp6g-796f-39vpx-refsource-confirm, exploit, vendor-advisory
https://github.com/cesanta/mongoose/pull/3611x-refsource-misc, issue-tracking, patch
https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71x-refsource-misc, patch
https://github.com/cesanta/mongoose/releases/tag/7.22x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.