CVE-2026-19538: Nlnetlabs Nsd

High severity, CVSS 7.5. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• Nlnetlabs Nsd: from 4.8.0, before 4.15.1 (fixed in 4.15.1)

Published 2026-08-26. Last modified 2026-09-08.