CVE-2026-96405

Aggregate DNS name chained pointer decompression work leads to degradation of service.

Published Oct 21, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
NLnet Labs Unbound up to and including version 1.26.1 limits compression-pointer traversal for each individual domain-name operation but has no aggregate inbound decompression-work budget. Many chained compression pointers in a message results in a lot of CPU usage following them. A malicious actor with recursive-query access and control of an ordinarily delegated authority that serves specially crafted replies can exploit the vulnerability and degrade Unbound's general performance.

Remediation

Vendor Solution

This issue is fixed starting with version 1.26.2

Tracking

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Advisories

Source ID Title
Debian DSA Debian DSA DSA-6581-1 unbound security update
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Nlnetlabs
Nlnetlabs unbound
Vendors & Products Nlnetlabs
Nlnetlabs unbound
Type Values Removed Values Added
Description NLnet Labs Unbound up to and including version 1.26.1 limits compression-pointer traversal for each individual domain-name operation but has no aggregate inbound decompression-work budget. Many chained compression pointers in a message results in a lot of CPU usage following them. A malicious actor with recursive-query access and control of an ordinarily delegated authority that serves specially crafted replies can exploit the vulnerability and degrade Unbound's general performance.
Title Aggregate DNS name chained pointer decompression work leads to degradation of service.
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
NLnet Labs
Published
Updated
Oct 29, 2026, 7:07 PM
Reserved
Oct 14, 2026, 9:16 AM
Status
Awaiting Analysis
Published
Oct 21, 2026, 9:17 AM
Modified
Oct 29, 2026, 7:17 PM