# CVE-2026-18309: GIMP integer overflow in APNG file parsing

Source: https://junglewise.ai/threats/cve-2026-18309-gimp-integer-overflow-in-apng-file-parsing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-20. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-18309 · Severity: high · CVSS 7.8 · Published 2026-08-20

GIMP is a widely-used image editing application. A flaw in how it processes APNG image files can be exploited by attackers who trick users into opening a malicious image, allowing execution of arbitrary code with the privileges of the user running GIMP. This could lead to unauthorized access to files, data theft, or further system compromise.

Technologies: [Gimp](https://junglewise.ai/threats/technologies/gimp). Vendors: [Gimp](https://junglewise.ai/threats/vendors/gimp).

## Quick answers

**Is CVE-2026-18309 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-18309 being exploited in the wild.

**How severe is CVE-2026-18309?** High severity, with a CVSS score of 7.8, published 20 August 2026.

**Which products and versions are affected?** GIMP GIMP.

**Is there a fix for CVE-2026-18309?** A patch was published on 2026-07-29: Fix released by GIMP Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-18309 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-18309?** Check whether you run Gimp. 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

The vulnerability is an integer overflow in GIMP's APNG (Animated PNG) file parser. The root cause is insufficient validation of user-supplied data when parsing APNG headers, which can trigger an integer overflow during buffer allocation. The attack requires user interaction—a target must be tricked into opening a malicious APNG file via a web page or direct file access. A successful exploit grants arbitrary code execution in the current user's security context. GIMP has released a patch, with details available in commit c760c8309d18bdf5259f1e04ced0779462c7c636.

## Affected products

- GIMP GIMP

## Timeline

- 2026-04-17: disclosed: Vulnerability reported to vendor
- 2026-07-29: patched: Fix released by GIMP
- 2026-07-29: advisory: Public advisory released (ZDI-26-462 / CVE-2026-18309)

## References

- [https://gitlab.gnome.org/GNOME/gimp/-/commit/c760c8309d18bdf5259f1e04ced0779462c7c636](https://gitlab.gnome.org/GNOME/gimp/-/commit/c760c8309d18bdf5259f1e04ced0779462c7c636)
- [https://www.zerodayinitiative.com/advisories/ZDI-26-462/](https://www.zerodayinitiative.com/advisories/ZDI-26-462/)

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- [GIMP use-after-free in XCF loader](https://junglewise.ai/threats/cve-2026-112258-a-flaw-was-found-in-gimp-the-xcf-loader-can-leave-a-dangling)
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