CVE-2026-100659

Netty 4.2.0 through 4.2.17 HTTP/3 Request Routing Bypass

Published Sep 26, 2026 CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Title Netty 4.2.0 through 4.2.18 HTTP/3 Request Routing Bypass Netty 4.2.0 through 4.2.17 HTTP/3 Request Routing Bypass
Type Values Removed Values Added
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.
Title Netty 4.2.0 through 4.2.18 HTTP/3 Request Routing Bypass
First Time appeared Netty
Netty netty
Weaknesses CWE-444
CPEs cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*
Vendors & Products Netty
Netty netty
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Sep 28, 2026, 6:17 PM
Reserved
Sep 26, 2026, 2:33 AM
Status
Deferred
Published
Sep 26, 2026, 2:16 PM
Modified
Sep 28, 2026, 7:16 PM
Severity
Moderate
Public date
Sep 26, 2026, 1:23 PM