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CVE-2026-81642

9.8, critical

NLnet Labs Unbound Heap-based Buffer Overflow Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
9.8, critical critical CVSS v3.1
EPSS, next 30 days
1% higher than 60.9% of scored CVEs
Exploitation
No public evidence
Published
16 Sept 2026a month ago

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.

Details

Vendor
NLnet Labs
Product
Unbound
Weakness
CWE-122 (opens in a new tab)
Status
Analyzed
Updated
22 Sept 2026
Assigner
sep@nlnetlabs.nl

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References 1

Patches and fixes 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other NLnet Labs CVEs

Every NLnet Labs CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-82717 NLnet Labs Unbound Heap-based Buffer Overflow Vulnerability EPSS 0.8% 9.8, critical
  • CVE-2026-80225 NLnet Labs Unbound Allocation of Resources Without Limits or Throttling Vulnerability EPSS 0.5% 7.5, high
  • CVE-2026-85501 NLnet Labs Unbound Allocation of Resources Without Limits or Throttling Vulnerability EPSS 0.5% 7.5, high
  • CVE-2026-18664 NLnet Labs NSD Improper Access Control Vulnerability EPSS 0.3% 9.1, critical
  • CVE-2026-18916 NLnet Labs NSD Integer Underflow Vulnerability EPSS 0.3% 7.5, high
  • CVE-2026-19401 NLnet Labs NSD Uncontrolled Resource Consumption Vulnerability EPSS 0.3% 7.5, high
  • CVE-2026-19538 The BLOCKED access control list items that are evaluated to deny access on the the proxy protocol port can be bypassed completely when… EPSS 0.2% 7.5, high

Beyond this page

Is CVE-2026-81642 in your network?

This page tells you how dangerous CVE-2026-81642 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 18 Oct 2026, not the live upstream state.