# CVE-2026-52584: libjxl heap buffer overflow in DecodeImageAPNG

Source: https://junglewise.ai/threats/cve-2026-52584-libjxl-heap-buffer-overflow-in-decodeimageapng  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-17. Updated: 2026-07-17  
License: CC BY 4.0 with a link back

CVE-2026-52584 · Severity: info · CVSS 0 · Published 2026-07-17

libjxl is an open-source library used for encoding and decoding JPEG XL images. A security flaw was discovered where the library incorrectly handles certain animated PNG (APNG) files, which could allow a local attacker to access sensitive information from the computer's memory. This could lead to the exposure of private data or help an attacker bypass other security protections on the system.

## Quick answers

**Is CVE-2026-52584 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-52584 being exploited in the wild.

**How severe is CVE-2026-52584?** Informational severity, with a CVSS score of 0, published 17 July 2026.

**Which products and versions are affected?** libjxl libjxl v0.11.2 and earlier.

**Is there a fix for CVE-2026-52584?** A patch was published on 2026-05-27: Fix submitted and approved via pull request Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-52584 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-52584?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A heap-based buffer overflow vulnerability exists in libjxl's APNG decoding logic within the `DecodeImageAPNG` function in `lib/extras/dec/apng.cc`. The flaw is triggered when the library fails to properly validate `frameRaw.rows` bounds before memory access during the decoding of an animated PNG. A local attacker can exploit this by providing a specially crafted APNG file to an application using the library (such as the `cjxl` tool). This results in an out-of-bounds read, potentially leaking sensitive information from the heap. A fix was submitted in pull request #4804 involving improved bounds validation.

## Affected products

- libjxl libjxl v0.11.2 and earlier

## Timeline

- 2026-05-26: disclosed: Issue reported on GitHub
- 2026-05-27: patched: Fix submitted and approved via pull request
- 2026-07-17: advisory: CVE published to NVD

## References

- [https://github.com/libjxl/libjxl/issues/4803](https://github.com/libjxl/libjxl/issues/4803)
- [https://github.com/libjxl/libjxl/pull/4804](https://github.com/libjxl/libjxl/pull/4804)