Description
In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in the DNSSEC validator that enables denial of service and possible remote code execution as a result of digesting DNSKEYs. A DNSKEY with an owner compression pointer to its own RDATA can overflow the digest buffer. Remote code execution is possible through attacker controlled data. An adversary can exploit the vulnerability by controlling a malicious zone and querying a vulnerable Unbound.
Published: 2026-09-16
Score: 9.1 Critical
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

Vendor Solution

This issue is fixed starting with version 1.26.1

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History

Wed, 16 Sep 2026 08:45:00 +0000

Type Values Removed Values Added
Description In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in the DNSSEC validator that enables denial of service and possible remote code execution as a result of digesting DNSKEYs. A DNSKEY with an owner compression pointer to its own RDATA can overflow the digest buffer. Remote code execution is possible through attacker controlled data. An adversary can exploit the vulnerability by controlling a malicious zone and querying a vulnerable Unbound.
Title Heap buffer overflow and possible Remote Code Execution when digesting DNSKEY
Weaknesses CWE-122
References
Metrics cvssV4_0

{'score': 9.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/U:Red'}

Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: NLnet Labs

Published:

Updated: 2026-09-16T08:30:58.604Z

Reserved: 2026-09-07T14:06:21.956Z

Link: CVE-2026-81642

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-16T09:17:06.320

Modified: 2026-09-16T09:17:06.320

Link: CVE-2026-81642

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses