Detections
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Amazon Linux 2023 : libpng, libpng-devel, libpng-static (ALAS2023-2026-1563)

high Nessus Plugin ID 306212

Synopsis

The remote Amazon Linux 2023 host is missing a security update.

Description

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1563 advisory.

 LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.2.1 through 1.6.55, `png_set_tRNS` and `png_set_PLTE` each alias a heap-allocated buffer between `png_struct` and `png_info`, sharing a single allocation across two structs with independent lifetimes. The `trans_alpha` aliasing has been present since at least libpng 1.0, and the `palette` aliasing since at least 1.2.1. Both affect all prior release lines `png_set_tRNS` sets `png_ptr->trans_alpha = info_ptr->trans_alpha` (256-byte buffer) and `png_set_PLTE` sets `info_ptr->palette = png_ptr->palette` (768-byte buffer). In both cases, calling `png_free_data` (with `PNG_FREE_TRNS` or `PNG_FREE_PLTE`) frees the buffer through `info_ptr` while the corresponding `png_ptr` pointer remains dangling. Subsequent row-transform functions dereference and, in some code paths, write to the freed memory. A second call to `png_set_tRNS` or `png_set_PLTE` has the same effect, because both functions call `png_free_data` internally before reallocating the `info_ptr` buffer. Version 1.6.56 fixes the issue.

 NOTE: https://github.com/pnggroup/libpng/security/advisories/GHSA-m4pc-p4q3-4c7jNOTE:
 https://github.com/pnggroup/libpng/pull/824NOTE: Fixed by:
 https://github.com/pnggroup/libpng/commit/23019269764e35ed8458e517f1897bd3c54820eb (v1.6.56)NOTE: Fixed by: https://github.com/pnggroup/libpng/commit/a3a21443ed12bfa1ef46fa0d4fb2b74a0fa34a25 (v1.6.56)NOTE:
 Fixed by: https://github.com/pnggroup/libpng/commit/7ea9eea884a2328cc7fdcb3c0c00246a50d90667 (v1.6.56)NOTE: Fixed by:
 https://github.com/pnggroup/libpng/commit/c1b0318b393c90679e6fa5bc1d329fd5d5012ec1 (v1.6.56) (CVE-2026-33416)

 LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.6.36 through 1.6.55, an out-of-bounds read and write exists in libpng's ARM/AArch64 Neon-optimized palette expansion path. When expanding 8-bit paletted rows to RGB or RGBA, the Neon loop processes a final partial chunk without verifying that enough input pixels remain. Because the implementation works backward from the end of the row, the final iteration dereferences pointers before the start of the row buffer (OOB read) and writes expanded pixel data to the same underflowed positions (OOB write). This is reachable via normal decoding of attacker-controlled PNG input if Neon is enabled. Version 1.6.56 fixes the issue.

 NOTE: https://github.com/pnggroup/libpng/security/advisories/GHSA-wjr5-c57x-95m2NOTE: Introduced with:
 https://github.com/pnggroup/libpng/commit/7734cda20cf1236aef60f3bbd2267c97bbb40869 (v1.6.36)NOTE: Fixed by: https://github.com/pnggroup/libpng/commit/aba9f18eba870d14fb52c5ba5d73451349e339c3 (v1.6.56) (CVE-2026-33636)

Tenable has extracted the preceding description block directly from the tested product 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

Run 'dnf update libpng --releasever 2023.11.20260413' or or 'dnf update --advisory ALAS2023-2026-1563 --releasever 2023.11.20260413' to update your system.

See Also

https://alas.aws.amazon.com//AL2023/ALAS2023-2026-1563.html

https://alas.aws.amazon.com/faqs.html

https://explore.alas.aws.amazon.com/CVE-2026-33416.html

https://explore.alas.aws.amazon.com/CVE-2026-33636.html

Plugin Details

Severity: High

ID: 306212

File Name: al2023_ALAS2023-2026-1563.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 4/13/2026

Updated: 4/13/2026

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

Risk Information

VPR

Risk Factor: High

Score: 7.4

CVSS v2

Risk Factor: High

Base Score: 9

Temporal Score: 7

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

CVSS Score Source: CVE-2026-33636

CVSS v3

Risk Factor: High

Base Score: 7.6

Temporal Score: 6.8

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

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:libpng-debuginfo, p-cpe:/a:amazon:linux:libpng, p-cpe:/a:amazon:linux:libpng-debugsource, p-cpe:/a:amazon:linux:libpng-static, p-cpe:/a:amazon:linux:libpng-tools, cpe:/o:amazon:linux:2023, p-cpe:/a:amazon:linux:libpng-devel, p-cpe:/a:amazon:linux:libpng-tools-debuginfo, p-cpe:/a:amazon:linux:libpng-devel-debuginfo

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/13/2026

Vulnerability Publication Date: 3/10/2026

Reference Information

CVE: CVE-2026-33416, CVE-2026-33636

IAVA: 2026-A-0272