CVE-2026-19538

Bypass of BLOCKED ACL items on proxy protocol port over TCP or TLS

State: Published
Severity: 8.2 High
Published: Aug 26, 2026
Updated: Aug 26, 2026
Reserved: Aug 11, 2026

Description

The BLOCKED access control list items that are evaluated to deny access on the the proxy protocol port can be bypassed completely when connecting over TCP or TLS and sending the query twice on connection that is kept open.

Scores

CVSS	Score	Vector	Source
4.0	8.2 High	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N	NLnet Labs

Weaknesses

CWE-290 Authentication Bypass by Spoofing
CWE-672 Operation on a Resource after Expiration or Release

Affected Products

Product	Versions
NSDNLnet Labs	4.8.0 to before 4.15.1Affected

References

https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-19538.txtvendor-advisory

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