CVE-2026-42944
Published: 20 May 2026
Summary
CVE-2026-42944 is a high-severity Numeric Truncation Error (CWE-197) vulnerability in Nlnetlabs Unbound. Its CVSS base score is 7.5 (High).
Operationally, ranked at the 12.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.
NVD 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'…
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(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.
Deeper analysisAI
Automated synthesis unavailable for this CVE.
Details
- CWE(s)
Affected Products
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-31085