Improper validation of certificate with host mismatch in Netty - #VU141317
Published: August 8, 2026
Vulnerability identifier: #VU141317
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-297
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass TLS hostname verification and disclose sensitive information.
The vulnerability exists due to improper validation of certificate with host mismatch in the OpenSSL client path when using a plain X509TrustManager and trust-manager wrapping is unavailable. A remote attacker can present a certificate for a mismatched hostname to bypass TLS hostname verification and disclose sensitive information.
This affects the SslProvider.OPENSSL path on Java 25+ when Unsafe-based reflection is unavailable and a non-extended X509TrustManager is used.
Affected software
Netty
Remediation
Install security update from vendor's website.
Netty - addressed in versions 4.1.137, 4.2.17