CVE-2026-128239
GPAC through 26.07.0 NULL Pointer Dereference via MPEG-4 Form Handlers
GPAC through 26.07.0 contains a NULL pointer dereference vulnerability in the MPEG-4 Form spatial-constraint handlers in src/compositor/mpeg4_form.c that lets attackers crash the process via unchecked group lookups. Attackers can supply a crafted XMT scene whose Form constraints reference a non-existent group, crashing tools like MP4Box during chapter import for denial of service.
Fixes and workarounds
Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: VulnCheckAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| gpac gpac gpac/gpac
github |
≥ 0; ≤ 26.07.0 (affected, custom)
Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 6.8 medium |
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 | CNA: VulnCheck |
| 3.1 / 5.5 medium |
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H | CNA: VulnCheck |
| 4.0 / 6.8 medium |
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD: [email protected] |
| 3.1 / 5.5 medium |
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H | NVD: [email protected] |
Exploit evidence
References
- https://github.com/gpac/gpac/issues/4029CNA: VulnCheck · issue-tracking
- https://github.com/gpac/gpac/commit/bc416b997622e43de65afab3bae9b7d05d72f2b0CNA: VulnCheck · patch
- https://github.com/gpac/gpac/blob/v26.07.0/src/compositor/mpeg4_form.c#L620-L621CNA: VulnCheck · technical-description
- https://github.com/sigdevel/pocs/blob/main/res/gpac/MP4Box/221/221_ab_apply_compositor_mpeg4_form_c_627.xmtCNA: VulnCheck · exploit
- https://github.com/gpac/gpacCNA: VulnCheck · product
- https://www.vulncheck.com/advisories/gpac-through-26.07.0-null-pointer-dereference-via-mpeg-4-form-handlersCNA: VulnCheck · third-party-advisory
- https://github.com/gpac/gpac[email protected]
- https://github.com/gpac/gpac/blob/v26.07.0/src/compositor/mpeg4_form.c#L620-L621[email protected]
- https://github.com/gpac/gpac/commit/bc416b997622e43de65afab3bae9b7d05d72f2b0[email protected]
- https://github.com/gpac/gpac/issues/4029[email protected]
- https://github.com/sigdevel/pocs/blob/main/res/gpac/MP4Box/221/221_ab_apply_compositor_mpeg4_form_c_627.xmt[email protected]
- https://www.vulncheck.com/advisories/gpac-through-26.07.0-null-pointer-dereference-via-mpeg-4-form-handlers[email protected]
For agents and automation
Read public disclosures for free as Markdown or JSON. Compatible browsers also expose native WebMCP tools to search disclosures, read this page, and discover API access.
Use the ontology-linked Cyber API with x402 pay per request, or a Y2 Pro or Elite API key with the intel:cyber scope.
Endpoints and access details
https://api.y2.dev/api/v2/cyber/cveshttps://api.y2.dev/api/v2/cyber/cves/{cveId}
A workspace owner or admin can create a Pro or Elite API key. Send Authorization: Bearer <Y2_API_KEY> from your trusted agent runtime.
For x402, omit Authorization and read the HTTP 402 payment challenge before signing a retry. Public browser tools do not make payments.