Debian dsa-6581 : libunbound-dev - security update

medium Nessus Plugin ID 371252

Synopsis

The remote Debian host is missing one or more security-related updates.

Description

The remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6581 advisory.

- ------------------------------------------------------------------------- Debian Security Advisory DSA-6581-1 [email protected] https://www.debian.org/security/ Yves-Alexis Perez October 23, 2026 https://www.debian.org/security/faq
- -------------------------------------------------------------------------

Package : unbound CVE ID : CVE-2026-35501 CVE-2026-50106 CVE-2026-96405 CVE-2026-97206 CVE-2026-109125

Multiple security vulnerabilities were discovered in Unbound, a validating, recursive, caching DNS resolver.

CVE-2026-35501

(DNSSEC) Bypass of a configured island trust anchor underneath an insecure parent from an attacker-controlled NSEC record.

CVE-2026-50106

(DNSSEC) Possible insecure NXDOMAIN for non-existing records under a configured island trust anchor underneath an insecure parent.

CVE-2026-96405

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

CVE-2026-97206

DNS-over-QUIC path-migration can lead to use-after-free on multi-threaded deployments, leading to potential denial of service.

CVE-2026-109125

Possible cache poisoning vulnerability via a cache side-channel exposed by 'unwanted-reply-threshold'.

For the stable distribution (trixie), these problems have been fixed in version 1.26.2-0+deb13u1.

We recommend that you upgrade your unbound packages.

For the detailed security status of unbound please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/unbound

Further information about Debian Security Advisories, how to apply these updates to your system and frequently asked questions can be found at: https://www.debian.org/security/

Mailing list: [email protected]

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Upgrade the libunbound-dev packages.

Plugin Details

Severity: Medium

ID: 371252

File Name: debian_DSA-6581.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Debian Local Security Checks

Published: 10/23/2026

Updated: 10/23/2026

Supported Sensors: Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.5

Percentile: 51.44

CVSS v2

Risk Factor: Medium

Base Score: 6.1

Temporal Score: 4.5

Vector: CVSS2#AV:N/AC:H/Au:N/C:N/I:P/A:C

CVSS Score Source: CVE-2026-50106

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.7

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:13.0, p-cpe:/a:debian:debian_linux:libunbound-dev, p-cpe:/a:debian:debian_linux:libunbound8, p-cpe:/a:debian:debian_linux:python3-unbound, p-cpe:/a:debian:debian_linux:unbound-anchor, p-cpe:/a:debian:debian_linux:unbound-host, p-cpe:/a:debian:debian_linux:unbound

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Ease: No known exploits are available

Patch Publication Date: 10/23/2026

Vulnerability Publication Date: 10/21/2026

Reference Information

CVE: CVE-2026-109125, CVE-2026-35501, CVE-2026-50106, CVE-2026-96405, CVE-2026-97206

IAVA: 2026-A-1194

Detections

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