CVE-2026-100665 Netty 4.2.11 through 4.2.17 QUIC Hostname Verification Bypass
Attackers can bypass QUIC hostname verification in Netty when using plain trust managers, allowing man-in-the-middle attacks against clients configured for HTTPS verification.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-100665?
CVE-2026-100665 is a high-severity vulnerability in netty, published on 26 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Netty versions from 4.2.11.Final before 4.2.18.Final contain an incomplete hostname verification fix in the QUIC certificate verification path when using a plain X509TrustManager. The BoringSSLCertificateVerifyCallback discards the SSLEngine for plain trust managers, preventing endpoint identification from running even when HTTPS verification is configured. Attackers on the network path can present a certificate chain for the wrong hostname that the plain trust manager accepts, bypassing hostname authentication for QUIC clients.
Weakness: CWE-295
Which versions are affected by CVE-2026-100665?
How do I fix CVE-2026-100665?
No fix has been published for CVE-2026-100665 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-100665 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100665 exists.
Sources
Also known as GHSA-4qw4-fmqv-qhv8, GHSA-mj35-3qqm-q387, UBUNTU-CVE-2026-100665.