TI-2026-64821 Aliases CVE-2026-100665 GHSA-4qw4-fmqv-qhv8

Netty 4.2.11 through 4.2.17 QUIC Hostname Verification Bypass

HIGH 77CWE-295Published 2026-09-26 · Updated 2026-10-02

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: Spoofing
Confidentiality · integrity · availability: High · None · None
Fix status: Partial Red Hat: 1 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-295.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00367 30th percentileScored 2026-11-07

Fix Partial netty (netty): 4.2.18.FinalRed Hat: 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
netty	netty	4.2.11.Final to before 4.2.18.Final	4.2.18.Final	Patch available	CNA

netty Vendornetty Affected 4.2.11.Final to before 4.2.18.Final Fixed in 4.2.18.Final Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:netty:netty::::::::	—	—	netty

cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:* Versions — — ·netty

Remediation

Fix · CNA netty (netty) Fixed in 4.2.18.Final

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Release · 2026-09-26
netty 4.2.18.Final
7 records Highest priority Priority HIGH 4 HIGH, 2 MEDIUM, 1 LOW
Other records, highest priority first
- TI-2026-64818 Netty HTTP/3 QPACK encoder-stream unbounded memory exhaustion DoSPriority HIGH 77
- TI-2026-64816 Netty before 4.2.18.Final QpackEncoder Unbounded Memory RetentionPriority HIGH 77
- TI-2026-64819 Netty HTTP/1 CONNECT authority-form mistranslated to malformed HTTP/3Priority HIGH 71
Show all 7 records →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat OpenShift Dev Spaces	Affected	No fix yet

Not affected: 1 product

Red Hat OpenShift AI (RHOAI)

Timeline

2026-10-02 Threatist record created from CVE-2026-100665
2026-10-03 Alias added: GHSA-4qw4-fmqv-qhv8

References

Patch 2

Advisory 1

GitHub Security Advisory (GHSA-mj35-3qqm-q387)

TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
TI-2026-30861 Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization CVSS 3.1CRITICAL 9.8
TI-2026-30864 Netty: HttpClientCodec response desynchronization CVSS 3.1CRITICAL 9.1
TI-2026-30859 Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder) CVSS 3.1CRITICAL 9.1
TI-2026-64818 Netty HTTP/3 QPACK encoder-stream unbounded memory exhaustion DoS CVSS 4.0HIGH 8.7
TI-2026-64816 Netty before 4.2.18.Final QpackEncoder Unbounded Memory Retention CVSS 4.0HIGH 8.7

See all 114 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences