Vulnerability · Published Oct 21, 2026 · Assigned by NLnet Labs

CVE-2026-96405Aggregate DNS name chained pointer decompression work leads to degradation of service.

Medium 5.3

In plain English

A medium-severity resource allocation without limits in Unbound from NLnet Labs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 17% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.3%top 83.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	unbound	no fix listed	DEBIAN-CVE-2026-96405
Debian:13	unbound	1.26.2-0+deb13u1	DEBIAN-CVE-2026-96405
Debian:14	unbound	1.26.2-1	DEBIAN-CVE-2026-96405
Ubuntu:22.04:LTS	unbound	no fix listed	UBUNTU-CVE-2026-96405
Ubuntu:24.04:LTS	unbound	no fix listed	UBUNTU-CVE-2026-96405
Ubuntu:26.04:LTS	unbound	no fix listed	UBUNTU-CVE-2026-96405
Ubuntu:26.10	unbound	no fix listed	UBUNTU-CVE-2026-96405

Affected products (as reported)

Vendor	Product	Versions
NLnet Labs	Unbound	0 – before 1.26.2

Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-96405.txt vendor-advisory