Improper Certificate Validation in Mongoose - CVE-2026-73253
Published: August 12, 2026
Vulnerability identifier: #VU142195
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-73253
CWE-ID: CWE-295
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass TLS hostname verification and perform a man-in-the-middle attack.
The vulnerability exists due to improper certificate validation in the built-in TLS hostname verification logic when comparing certificate SAN/CN values against the expected hostname. A remote attacker can present a wildcard certificate that matches more hostnames than intended to bypass TLS hostname verification and perform a man-in-the-middle attack.
Both SAN and CN verification paths are affected.
Affected software
Mongoose
How to mitigate CVE-2026-73253
Install security update from vendor's website.
Mongoose - update to 7.22