CVE-2026-100663

highpriority · track · 30EPSS 0.003 · 23 %ileDE

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.30% (23rd) EPSS

CVSS 7.5 · high

Is it mine?

8 products

Check your exposure

Who says so?

1 sources

cert_bund

EPSS · scored 2026-10-28

Netty's HTTP/3 codec (io.netty:netty-codec-http3) from 4.2.2.Final through 4.2.17.Final does not special-case HTTP/1 CONNECT authority-form request-targets when converting HTTP/1 messages to HTTP/3 in HttpConversionUtil.toHttp3Headers. The authority-form target (e.g., "CONNECT trusted.example:443") is parsed as a URI, so its host is emitted as :scheme, :path is set to "/", and the HTTP/1 Host header is used as :authority; if no Host header is present the CONNECT target is dropped. In a Netty-based HTTP/1-to-HTTP/3 proxy or gateway, a remote client can send a CONNECT request whose Host header names a different authority than the request-target, producing a malformed HTTP/3 CONNECT whose tunnel :authority is attacker-controlled. This can bypass tunnel allow-lists, egress policy, backend selection, or audit controls that validate the HTTP/1 CONNECT request-target before forwarding over HTTP/3. The issue is fixed in 4.2.18.Final.

cvss

Technical severity, 0–10. One row per scoring source.

8.7

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.6–8.7

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Nprimary · disclosure@vulncheck.comexploitability 3.9 · impact 3.6

v4.08.7highCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Xsecondary · disclosure@vulncheck.com

v4.06.6mediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Xsecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: no · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-20US

affected products (8)

Products and version ranges known to be affected.

IBM SPSS Analytic Serverall versionscert_bundDEcpe:/a:ibm:spss:analytic_server
Red Hat Enterprise Linuxall versionscert_bundDEcpe:/o:redhat:enterprise_linux:-
SUSE Linuxall versionscert_bundDEcpe:/o:suse:suse_linux:-
SUSE openSUSEall versionscert_bundDEcpe:/o:suse:opensuse:-
Open Source Netty< 4.1.138.Finalcert_bundDE
Open Source Netty< 4.2.18.Finalcert_bundDE
Open Source Open Source Netty <4.1.138.Final< 4.1.138.Finalcert_bundDE
Open Source Open Source Netty <4.2.18.Final< 4.2.18.Finalcert_bundDE

advisories (1)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-3291Netty: Mehrere SchwachstellenDeutsch2026-09-09csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Netty ausnutzen, um Denial-of-Service-Zustände zu verursachen, Sicherheitsmaßnahmen zu umgehen, Request- oder Response-Smuggling durchzuführen sowie Daten offenzulegen oder zu manipulieren.

sources

Which sources assert this record, and when.

cert_bund NVD CVE.org MITRE

published 2026-09-26modified 2026-09-28

references (2) nvd

External citations — patches, advisories, analysis.

scry

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