CVE-2026-62243 PUBLISHED

Netty 4.2.0 through 4.2.16 TLS Hostname Verification Bypass

Assigner: VulnCheck
Reserved: 13.07.2026 Published: 22.08.2026 Updated: 22.08.2026

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.

Metrics

CVSS Vector: 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
CVSS Score: 8.7

Product Status

Vendor netty
Product netty
Versions Default: unaffected
  • affected from 4.2.0.Final to 4.2.16.Final (excl.)
  • Version 4.2.16.Final is unaffected
Vendor netty
Product netty
Versions Default: unaffected
  • affected from 0 to 4.1.137.Final (excl.)
  • Version 4.1.137.Final is unaffected

Credits

  • violetagg reporter

References

Problem Types

  • Improper Validation of Certificate with Host Mismatch CWE