CVE-2026-100664 Netty - Broken Access Control

Netty io.netty:netty-codec-http3 4.2.2.Final through 4.2.17.Final contains an authority confusion vulnerability caused by incorrect precedence of Host header over request-target authority in HTTP/3 :authority pseudo-header construction, letting remote attackers cause inconsistent routing and authorization decisions, exploit requires crafted HTTP/1 requests with conflicting Host headers.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.33% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Broken Access Control
Impact
Data Tampering
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Published
26 September 2026
Updated
15 October 2026
Weakness
CWE-20

Vendor fix

Upgrade to version 4.2.18.Final or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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