# CVE-2026-71613: GPAC buffer overflow in j2kdec_process JP2 decoder

Source: https://junglewise.ai/threats/cve-2026-71613-gpac-buffer-overflow-in-j2kdec-process-jp2-decoder  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-09. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-71613 · Severity: high · CVSS 7.8 · Published 2026-09-09

GPAC is an open-source multimedia framework used to process audio and video files. A buffer overflow vulnerability in its JPEG-2000 decoder allows an attacker to crash the application or potentially execute arbitrary code by providing a specially crafted JP2 file. This could impact any service or application using GPAC to decode multimedia content.

Technologies: [Gpac](https://junglewise.ai/threats/technologies/gpac). Vendors: [Gpac](https://junglewise.ai/threats/vendors/gpac).

## Quick answers

**Is CVE-2026-71613 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-71613 being exploited in the wild.

**How severe is CVE-2026-71613?** High severity, with a CVSS score of 7.8, published 9 September 2026.

**Which products and versions are affected?** Gpac c2dee3aff638cd96f9617ac5b17dc2868cd90ef3 and likely earlier.

**Is there a fix for CVE-2026-71613?** A patch was published on 2026-09-09: Fixed in commit 9a253a07fd3f6b48022bba74302bf39388dda859 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-71613 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-71613?** Check whether you run Gpac at an affected version. 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 buffer overflow exists in the j2kdec_process() function in src/filters/dec_j2k.c when processing JPEG-2000 (JP2) files. The vulnerability occurs because the output buffer size is calculated based on dimensions read from the IHDR box at line 402, but when a crafted JP2 file declares small dimensions in the IHDR box (e.g., 1×1) while the JPEG-2000 codestream's SIZ marker declares large dimensions (e.g., 4000×4000), the opj_decode() function produces pixel data at the codestream's actual resolution. The code then writes this large pixel data (~48MB) to a tiny buffer (~3 bytes), causing a heap overflow. The dimensions are updated later (lines 435-441) but the out_size is never recalculated. The vulnerability requires only providing a malicious JP2 file as input; no authentication or prior access is required. A proof-of-concept confirms the crash. The fix (commit 9a253a07fd3f6b48022bba74302bf39388dda859) moves the out_size calculation after dimension updates.

## Affected products

- GPAC GPAC c2dee3aff638cd96f9617ac5b17dc2868cd90ef3 and likely earlier

## Timeline

- 2026-06-11: disclosed: Vulnerability reported in GitHub issue #3613
- 2026-09-09: patched: Fixed in commit 9a253a07fd3f6b48022bba74302bf39388dda859
- 2026-09-09: advisory: CVE-2026-71613 published

## References

- [https://github.com/gpac/gpac/commit/9a253a07fd3f6b48022bba74302bf39388dda859](https://github.com/gpac/gpac/commit/9a253a07fd3f6b48022bba74302bf39388dda859)
- [https://github.com/gpac/gpac/issues/3613](https://github.com/gpac/gpac/issues/3613)

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