cvedb.io
CVE-2026-50251
MEDIUM · CVSS 5.3
EPSS exploitation probability: 0%
Published 2026-07-22T14:17:20.503 · Last modified 2026-07-22T15:17:18.500

Summary

In NLnet Labs Unbound up to and including version 1.25.1, when 'unwanted-reply-threshold' is enabled (set to any value greater than zero), glue records of 0.0.0.0/::0 can short-circuit Unbound, on systems that can direct such traffic, by issuing DNS queries and receiving seemingly unwanted replies since the remote IP does not match the original source IP of 0.0.0.0/::0. This behavior keeps on looping for the glue records and pushing the counter to the configured 'unwanted-reply-threshold' that triggers a defensive cache clear. A malicious actor who controls a delegation that returns in-bailiwick glue of 0.0.0.0/::0 can drive the counter to the limit of 'unwanted-reply-threshold' to the threshold and trigger a cache clean of the message and rrset caches; at will, indefinitely, without sendi

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.