CVE-2026-100659
Received Received - Intake

Netty HTTP/3 Authority Header Conflict Vulnerability

Publication date: 2026-09-26

Last updated on: 2026-09-26

Assigner: VulnCheck

Description
Netty's HTTP/3 codec (io.netty:netty-codec-http3) in versions 4.2.0.Final through 4.2.17.Final does not enforce the RFC 9114 requirement that the :authority pseudo-header field and a literal host header field, when both present, carry the same value. A remote unauthenticated peer can send a single HEADERS frame containing both fields with differing, attacker-controlled values; the request is accepted and delivered to the application with two conflicting authorities, allowing routing, virtual-host, and access-control decisions to be bypassed when different components in the request path consult different fields. This issue is fixed in 4.2.18.Final.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-09-26
Last Modified
2026-09-26
Generated
2026-09-26
AI Q&A
2026-09-26
EPSS Evaluated
N/A
NVD
CVE-2026-100659
EUVD
EUVD-2026-87753

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
netty netty_codec_http3 From 4.2.0.Final (inc) to 4.2.17.Final (inc)
netty netty_codec_http3 4.2.18.Final

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-444 The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

Netty's HTTP/3 codec does not enforce that the :authority pseudo-header and the Host header must match when both are present. This allows an attacker to send a request with conflicting authority values, bypassing routing, virtual-host, and access-control checks.

Impact Analysis

An attacker could exploit this to send requests that appear to come from different authorities, potentially bypassing security controls and accessing unauthorized resources or data.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. Compliance may be compromised if access controls are bypassed.

Mitigation Strategies

Upgrade Netty's HTTP/3 codec to version 4.2.18.Final or later to address the vulnerability.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-100659. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart