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Fencer Intel
medium 5.5

CVE-2026-128239 json

GPAC through 26.07.0 NULL Pointer Dereference via MPEG-4 Form Handlers

published 2d ago modified yesterday also EUVD-2026-125053

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits
0
none known

Summary

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.

Patch / fix

Is CVE-2026-128239 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
yesterday

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-14).

Exploits and checks

  • github.com https://github.com/sigdevel/pocs/blob/main/res/gpac/MP4Box/221/221_ab_apply_compositor_mpeg4_form_c_627.xmt referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.8 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 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CNA 4.0 6.8 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

Affected products

  • gpac gpac

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.