Linux Distros Unpatched Vulnerability : CVE-2026-33278

critical Nessus Plugin ID 315776

Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

- NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep- copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure. (CVE-2026-33278)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

Plugin Details

Severity: Critical

ID: 315776

File Name: unpatched_CVE_2026_33278.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Misc.

Published: 5/20/2026

Updated: 5/20/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.4

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

CVSS Score Source: CVE-2026-33278

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9

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:U/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:centos:centos:unbound-anchor, cpe:/o:debian:debian_linux:14.0, p-cpe:/a:redhat:enterprise_linux:unbound-anchor, cpe:/o:centos:centos:8, cpe:/o:centos:centos:7, cpe:/o:debian:debian_linux:11.0, p-cpe:/a:redhat:enterprise_linux:unbound, p-cpe:/a:redhat:enterprise_linux:unbound-libs, cpe:/o:redhat:enterprise_linux:8, cpe:/o:redhat:enterprise_linux:10, p-cpe:/a:centos:centos:unbound-devel, p-cpe:/a:centos:centos:python3-unbound, cpe:/o:debian:debian_linux:13.0, p-cpe:/a:centos:centos:unbound-libs, cpe:/o:redhat:enterprise_linux:7, p-cpe:/a:centos:centos:unbound-python, p-cpe:/a:centos:centos:unbound-dracut, cpe:/o:redhat:enterprise_linux:9, p-cpe:/a:redhat:enterprise_linux:unbound-utils, p-cpe:/a:debian:debian_linux:unbound, p-cpe:/a:redhat:enterprise_linux:unbound-dracut, p-cpe:/a:centos:centos:unbound, p-cpe:/a:redhat:enterprise_linux:unbound-devel, cpe:/o:debian:debian_linux:12.0, p-cpe:/a:redhat:enterprise_linux:unbound-python, p-cpe:/a:redhat:enterprise_linux:python3-unbound, p-cpe:/a:centos:centos:unbound-utils

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 5/20/2026

Reference Information

CVE: CVE-2026-33278

Detections

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