CVE-2026-100663

7.5 HIGHpublic exploit available

Published 2026-09-26 · Updated 2026-09-28

AI analysis for this CVE has not been generated yet. Raw NVD data is shown below.

NVD description

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 vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Weaknesses

CWE-20

Public exploit & PoC references

https://github.com/netty/netty/security/advisories/GHSA-jgph-cgq3-c627

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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