Linux Distros Unpatched Vulnerability : CVE-2026-40395

high Nessus Plugin ID 306145

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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.

- Varnish Enterprise before 6.0.16r12 allows a workspace overflow denial of service (daemon panic) for shared VCL. The headerplus.write_req0() function from vmod_headerplus updates the underlying req0, which is normally the original read-only request from which req is derived (readable and writable from VCL).
This is useful in the active VCL, after amending req, to prepare a refined req0 before switching to a different VCL with the return (vcl(<label>)) action. This is for example how the Varnish Controller operates shared VCL deployments. If the amended req contained too many header fields for req0, this would have resulted in a workspace overflow that would in turn trigger a panic and crash the Varnish Enterprise server. This could be used as a Denial of Service attack vector by malicious clients. (CVE-2026-40395)

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: High

ID: 306145

File Name: unpatched_CVE_2026_40395.nasl

Version: 1.4

Type: Local

Agent: unix

Family: Misc.

Published: 4/13/2026

Updated: 4/29/2026

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

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: Medium

Base Score: 5

Temporal Score: 4.3

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

CVSS Score Source: CVE-2026-40395

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.9

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

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, p-cpe:/a:redhat:enterprise_linux:varnish-docs, p-cpe:/a:centos:centos:varnish-modules, p-cpe:/a:centos:centos:varnish, cpe:/o:canonical:ubuntu_linux:25.10, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:centos:centos:8, p-cpe:/a:redhat:enterprise_linux:varnish-devel, p-cpe:/a:canonical:ubuntu_linux:varnish, p-cpe:/a:centos:centos:varnish-devel, cpe:/o:redhat:enterprise_linux:8, cpe:/o:canonical:ubuntu_linux:14.04:-:lts, p-cpe:/a:centos:centos:varnish-docs, p-cpe:/a:redhat:enterprise_linux:varnish, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, p-cpe:/a:redhat:enterprise_linux:varnish-modules, cpe:/o:canonical:ubuntu_linux:26.04, cpe:/o:canonical:ubuntu_linux:22.04:-:lts

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

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 4/12/2026

Reference Information

CVE: CVE-2026-40395

Detections

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