# CVE-2026-40930: LIBPNG: Chunk smuggling in push-mode APNG parser via unconsumed chunk body

CVE-2026-40930 is fixed in 6 products on 1 platform, first by DEBIAN-CVE-2026-40930, released May 27, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-40930
- Priority: Routine
- CVSS: 5.4 (Moderate)
- EPSS: 0.0020
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 4, 2026
- Weakness: Interpretation Conflict
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40930

## Description

LIBPNG is a reference library for use in applications that process PNG (Portable Network Graphics) raster image files. In version 1.8.0, three inter-frame chunk discard paths in the push-mode APNG parser clear the chunk-header flag without consuming the chunk body and CRC, allowing attacker-controlled bytes inside an ignored ancillary chunk to be reinterpreted as a fresh chunk header on the next call to `png_process_data`. Commit faf06924688b62d7c1654b5ceddedbde66ffadb4 fixes the issue.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | firefox amzn 2023 | 140.11.0-1.amzn2023.0.1 | [ALAS2023-2026-1793](https://patchblox.com/security/data/fix/linux/alas2023-2026-1793.md) | Jun 8, 2026 |
| Linux | firefox-debuginfo amzn 2023 | 140.11.0-1.amzn2023.0.1 | [ALAS2023-2026-1793](https://patchblox.com/security/data/fix/linux/alas2023-2026-1793.md) | Jun 8, 2026 |
| Linux | firefox-debugsource amzn 2023 | 140.11.0-1.amzn2023.0.1 | [ALAS2023-2026-1793](https://patchblox.com/security/data/fix/linux/alas2023-2026-1793.md) | Jun 8, 2026 |
| Linux | libpng-tools Ubuntu 20.04 LTS (focal) | 1.6.37-2ubuntu0.1~esm3 | [libpng-tools 1.6.37-2ubuntu0.1~esm3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libpng-tools-1.6.37-2ubuntu0.1-esm3.md) | Jun 4, 2026 |
| Linux | libpng-tools Ubuntu 22.04.1 LTS (jammy) | 1.6.37-3ubuntu0.6 | [libpng-tools 1.6.37-3ubuntu0.6](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libpng-tools-1.6.37-3ubuntu0.6.md) | Jun 4, 2026 |
| Linux | libpng1.6 Debian 12.15 (bookworm) | 1.6.37-4 | [DEBIAN-CVE-2026-40930](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40930.md) | May 27, 2026 |
| Linux | libpng1.6 Debian 13.5 (trixie) | 1.6.37-4 | [DEBIAN-CVE-2026-40930](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40930.md) | May 27, 2026 |
| Linux | libpng1.6 Debian 14 | 1.6.37-4 | [DEBIAN-CVE-2026-40930](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40930.md) | May 27, 2026 |
| Linux | libpng16-16 Ubuntu 20.04 LTS (focal) | 1.6.37-2ubuntu0.1~esm3 | [libpng16-16 1.6.37-2ubuntu0.1~esm3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libpng16-16-1.6.37-2ubuntu0.1-esm3.md) | Jun 4, 2026 |
| Linux | libpng16-16 Ubuntu 22.04.1 LTS (jammy) | 1.6.37-3ubuntu0.6 | [libpng16-16 1.6.37-3ubuntu0.6](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libpng16-16-1.6.37-3ubuntu0.6.md) | Jun 4, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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