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Incorrect Calculation of Buffer Size The advisory has been revoked - it doesn't affect any version of package unbound-utils  (opens in a new tab)

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EPSS
0.78% (54th percentile)

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  • Snyk IDSNYK-RHEL10-UNBOUNDUTILS-16785397
  • published21 May 2026
  • disclosed20 May 2026
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Introduced: 20 May 2026

CVE-2026-42944  (opens in a new tab)
CWE-131  (opens in a new tab)

Amendment

The Red Hat security team deemed this advisory irrelevant for RHEL:10.

NVD Description

Note: Versions mentioned in the description apply only to the upstream unbound-utils package and not the unbound-utils package as distributed by RHEL.

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-duplicate the EDNS options and a fix to prevent truncation of the EDNS field size calculation.