cvedb.io
CVE-2026-42944
HIGH · CVSS 7.5
EPSS exploitation probability: 0%
Published 2026-05-20T10:16:27.760 · Last modified 2026-06-30T03:19:42.120

Summary

NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a vulnerability that results in heap overflow when encoding multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options in the reply packet. The relevant options ('nsid', 'answer-cookie', 'pad-responses' (default)) need to be enabled for the vulnerability to be exploited. An adversary who can query Unbound can exploit the vulnerability by attaching multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options to the query. A flaw in the size calculation of the EDNS field truncates the correct value which allows the encoder to overflow the available space when writing. Those two combined lead to a heap overflow write of Unbound controlled data and eventually a crash. Unbound 1.25.1 contains a patch with a fix to de-dup

Affected products

nlnetlabs — unbound

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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.