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8.7 High

CVE-2026-42944 NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a vulnerability that results in heap overflow when…

Description

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.

Affected products and versions

Product Affected versions Fixed in
unbound 1.14 1.14.0 → < 1.25.1 1.25.1
Red Hat Enterprise Linux AppStream (v. 10) Versions not published
Red Hat Enterprise Linux AppStream (v. 8) Versions not published
Red Hat Enterprise Linux AppStream (v. 9) Versions not published
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) Versions not published
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) Versions not published
Red Hat Hardened Images 1.25 earliest → < 1.25.1-0.1.hum1 1.25.1-0.1.hum1
Red Hat Enterprise Linux 6 Versions not published
Red Hat Enterprise Linux 7 Versions not published
Show the 4 other branches
Product Affected versions Fixed in
Red Hat OpenShift Container Platform 4 Versions not published
Red Hat Enterprise Linux 10 Versions not published
Red Hat Enterprise Linux 8 Versions not published
Red Hat Enterprise Linux 9 Versions not published

References

Timeline

  1. Published
  2. Last modified

Other CVEs of unbound

The 58 CVEs of unbound →
CVE-2026-97206 NLnet Labs Unbound, 1.22.0 up to and including version 1.26.1, contains a DNS-over-QUIC (DoQ) lifetime bug reachable… 7.5 High CVE-2026-96405 NLnet Labs Unbound up to and including version 1.26.1 limits compression-pointer traversal for each individual… 5.3 Medium CVE-2026-50106 When NLnet Labs Unbound up to and including version 1.26.1 is configured with both a root trust anchor and an additional… 6.5 Medium CVE-2026-35501 When NLnet Labs Unbound 1.0.1 up to and including version 1.26.1 is configured with both a root trust anchor and an… 3.7 Low
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