# CVE-2026-79514: GPAC out-of-bounds read in downloader via chunked HTTP response

Source: https://junglewise.ai/threats/cve-2026-79514-gpac-out-of-bounds-read-in-downloader-via-chunked-http-response  
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-2026-79514 · Severity: medium · CVSS 6.5 · Published 2026-09-09

GPAC is an open-source multimedia framework used to process audio and video files. A vulnerability in its HTTP client allows a remote attacker to crash the application by sending a maliciously crafted HTTP response with a specially formatted chunk size, causing denial of service. An attacker could exploit this by hosting a malicious HTTP server or intercepting HTTP traffic to trigger the crash.

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

## Quick answers

**Is CVE-2026-79514 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-79514 being exploited in the wild.

**How severe is CVE-2026-79514?** Medium severity, with a CVSS score of 6.5, published 9 September 2026.

**Which products and versions are affected?** Gpac v26.07.0.

**Is there a fix for CVE-2026-79514?** A patch was published on 2026-09-09: Fixed in commit 2fd5a06ab226767900fd86edb5a1e8bfc1010640 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-79514 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-79514?** 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

An out-of-bounds read vulnerability exists in the gf_dm_data_received and gf_dm_get_chunk_data functions in src/utils/downloader.c. When processing a Transfer-Encoding: chunked HTTP response, the code parses the chunk size using sscanf("%x", &size) without validating the upper bound. A crafted first chunk size of 0xFFFFFFFF (4GB-1) bypasses a subsequent bounds check due to unsigned 32-bit integer wraparound: when hdr_size + 0xFFFFFFFF is computed, the result wraps to a small value, allowing nbBytes to remain 0xFFFFFFFF. This causes a subsequent memcpy to attempt reading 4GB-1 bytes from a ~4KB heap buffer, triggering an out-of-bounds read. The vulnerability is reached when the GPAC client connects to any HTTP URL, including DASH manifest segments. A fix is available in commit 2fd5a06.

## Affected products

- GPAC GPAC v26.07.0

## Timeline

- 2026-08-19: disclosed: Vulnerability reported via GitHub issue
- 2026-09-09: patched: Fixed in commit 2fd5a06ab226767900fd86edb5a1e8bfc1010640

## References

- [https://github.com/gpac/gpac/commit/2fd5a06ab226767900fd86edb5a1e8bfc1010640](https://github.com/gpac/gpac/commit/2fd5a06ab226767900fd86edb5a1e8bfc1010640)
- [https://github.com/gpac/gpac/issues/3861](https://github.com/gpac/gpac/issues/3861)

## Related threats

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