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RHEL 10 : unbound (RHSA-2026:23231)

critical Nessus Plugin ID 319496

Synopsis

The remote Red Hat host is missing one or more security updates for unbound.

Description

The remote Redhat Enterprise Linux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:23231 advisory.

 The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver.

 Security Fix(es):

 * unbound: Heap overflow and crash with multiple nsid, cookie, padding EDNS options (CVE-2026-42944)

 * unbound: Unbound DNSSEC Validator Denial of Service via Incorrect Write Offset Counter in Chase-Reply Messages (CVE-2026-42959)

 * unbound: Unbound DNSSEC Validator Use-After-Free via Deep Copy Pointer Overwrite Leading to DoS and Possible Remote Code Execution (CVE-2026-33278)

 For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux 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

Update the RHEL unbound package based on the guidance in RHSA-2026:23231.

See Also

https://access.redhat.com/security/updates/classification/#important

https://bugzilla.redhat.com/show_bug.cgi?id=2479774

https://bugzilla.redhat.com/show_bug.cgi?id=2479806

https://bugzilla.redhat.com/show_bug.cgi?id=2479808

http://www.nessus.org/u?bc674657

https://access.redhat.com/errata/RHSA-2026:23231

Plugin Details

Severity: Critical

ID: 319496

File Name: redhat-RHSA-2026-23231.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 6/6/2026

Updated: 6/6/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

Vendor

Vendor Severity: Important

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.4

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

CVSS Score Source: CVE-2026-33278

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.5

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

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

CVSS v4

Risk Factor: Critical

Base Score: 10

Threat Score: 9.1

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Vulnerability Information

CPE: p-cpe:/a:redhat:enterprise_linux:unbound-dracut, p-cpe:/a:redhat:enterprise_linux:unbound-libs, p-cpe:/a:redhat:enterprise_linux:unbound-anchor, p-cpe:/a:redhat:enterprise_linux:unbound-devel, p-cpe:/a:redhat:enterprise_linux:python3-unbound, p-cpe:/a:redhat:enterprise_linux:unbound, p-cpe:/a:redhat:enterprise_linux:unbound-utils, cpe:/o:redhat:enterprise_linux:10.2

Required KB Items: Host/local_checks_enabled, Host/RedHat/release, Host/RedHat/rpm-list, Host/cpu

Exploit Ease: No known exploits are available

Patch Publication Date: 6/4/2026

Vulnerability Publication Date: 5/20/2026

Reference Information

CVE: CVE-2026-33278, CVE-2026-42944, CVE-2026-42959

CWE: 416, 824

RHSA: 2026:23231