Linux Distros Unpatched Vulnerability : CVE-2026-56711

high Nessus Plugin ID 344522

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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.

- VLC media player computes the size of a picture buffer with 32-bit arithmetic and allocates from the wrapped result. In AllocatePicture in src/misc/picture.c the running total is accumulated as i_bytes += p->i_pitch * p->i_lines, and both plane_t fields are declared int in include/vlc_picture.h, so the multiplication is evaluated at 32 bits and wraps before it is widened to the size_t accumulator. The overflow check that precedes it divides in 64-bit arithmetic and therefore does not constrain the product, and the subsequent comparison against PICTURE_SW_SIZE_MAX examines the already wrapped value, so both guards pass. aligned_alloc then reserves the small wrapped size while the decoder writes scanlines sized from the original dimensions. A crafted PNG whose IHDR declares large width and height reaches this path through the image demuxer, whose only size guard is on the input file's byte count rather than the declared dimensions, and the decoder in modules/codec/png.c writes past the end of the allocation with attacker-influenced length and content. Opening the file directly or through a playlist entry is sufficient, with no non-default settings. (CVE-2026-56711)

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: 344522

File Name: unpatched_CVE_2026_56711.nasl

Version: 1.2

Type: Local

Agent: unix

Family: Misc.

Published: 9/10/2026

Updated: 9/11/2026

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

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 58.18

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 8.5

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

CVSS Score Source: CVE-2026-56711

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 8.1

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

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

CVSS v4

Risk Factor: High

Base Score: 8.6

Threat Score: 6.1

Threat Vector: CVSS:4.0/E:U

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:vlc

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: 9/9/2026

Reference Information

CVE: CVE-2026-56711

Detections

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