CVE-2026-19538
Description
A flaw was found in nsd. A remote attacker can bypass BLOCKED access control list (ACL) items on the proxy protocol port. This bypass occurs when connecting over TCP or TLS and sending the query twice on a persistent connection. This could allow unauthorized access or actions that should have been prevented by the ACL.
Statement
Red Hat Product Security has determined that this vulnerability does not affect any currently supported Red Hat product. This assessment may evolve based on further analysis and discovery. For more information about this vulnerability and the products it affects, please see the linked references.
Mitigation
To mitigate this issue, disable the proxy protocol feature in the `nsd` configuration if it is not required. This can typically be done by removing or commenting out proxy protocol related directives in the `nsd.conf` file. A restart of the `nsd` service will be required for the changes to take effect and may impact DNS resolution during the restart.
Understanding the Weakness (CWE)
Other
Technical Impact: Varies by Context
An attacker might be able to gain advantage over other users by performing the action multiple times, or affect the correctness of the product.
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