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CVE-2026-85501

7.5, high

NLnet Labs Unbound Allocation of Resources Without Limits or Throttling Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
7.5, high high CVSS v3.1
EPSS, next 30 days
0.5% higher than 40.1% of scored CVEs
Exploitation
No public evidence
Published
16 Sept 2026a month ago

Description

Novel vulnerabilities to launch algorithmic complexity attacks on DNSSEC have been researched under the term 'ReTrap'. These result in degradation of service when malicious zones are used to serve the algorithmic complexity vulnerabilities. NLnet Labs Unbound up to and including 1.26.0 is vulnerable to some of them. TagTrap, where the triple(Zone, Algo, KeyTag) matching mechanism introduces a significant attack vector when resolvers handle malicious responses containing numerous mismatched DNSKEY, RRSIG, and DS record. DelegationTrap, where constructing the chain-of-trust requires iterative validation of DNSKEY and DS records from the root zone downward. For deeply nested domains, this results in significant computational overhead. NsecTrap, where responses with excessive invalid NSEC records compel the resolver to validate each one. AdditionalTrap, where Unbound by default would try to DNSSEC validate the ADDITIONAL section as well. This can be exploited to waste validation resources by malicious users.

Details

Vendor
NLnet Labs
Product
Unbound
Weakness
CWE-770 (opens in a new tab)
Status
Analyzed
Updated
23 Sept 2026
Assigner
sep@nlnetlabs.nl

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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-2026-81642 NLnet Labs Unbound Heap-based Buffer Overflow Vulnerability EPSS 1% 9.8, critical
  • 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-2026-18664 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-2026-85501 in your network?

This page tells you how dangerous CVE-2026-85501 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 17 Oct 2026, not the live upstream state.