CVE-2026-100665

Netty 4.2.11 through 4.2.17 QUIC Hostname Verification Bypass

HIGH
7.5
CVSS Score
Published: September 26, 2026 at 01:23 PM UTC
Updated: October 2, 2026 at 04:16 PM UTC
1 product affected across 1 vendorNetty

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Severity
HIGH7.5
Exploit prediction
EPSS 0.4%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

4.2.11.final ≤ v < 4.2.18.final4.2.11.Final
Vendor states this is fixed in 4.2.18.Final (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-295

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