Vulnerability Description
Netty (io.netty:netty-handler) versions from 4.2.0.Final through 4.2.16.Final and versions through 4.1.136.Final disable TLS hostname verification on the SslProvider.OPENSSL client path when a plain (non-extended) X509TrustManager is used and Unsafe-based trust-manager wrapping is unavailable (Java 25+). In this configuration the OpenSSL client does not perform hostname verification, allowing a man-in-the-middle attacker to present a certificate issued for a different hostname that is accepted without validation. Fixed in 4.2.17.Final and 4.1.137.Final.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/netty/netty/security/advisories/GHSA-p85m-gvr3-788c
- https://www.vulncheck.com/advisories/netty-through-tls-hostname-verification-byp
FAQ
What is CVE-2026-62243?
CVE-2026-62243 is a vulnerability with a CVSS score of 7.5 (HIGH). Netty (io.netty:netty-handler) versions from 4.2.0.Final through 4.2.16.Final and versions through 4.1.136.Final disable TLS hostname verification on the SslProvider.OPENSSL client path when a plain (...
How severe is CVE-2026-62243?
CVE-2026-62243 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-62243?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.