Vulnerability · Published Feb 26, 2026 · Assigned by GitHub_M

CVE-2026-27821GPAC NHML Demuxer (dmx_nhml.c) Vulnerable to Stack Buffer Overflow

High 7.7

In plain English

A high-severity stack buffer overflow in gpac from gpac. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 26% of all known vulnerabilities).

Severity (CVSS 4.0)7.7High

Exploit odds (30 days)0.3%top 74.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

GPAC is an open-source multimedia framework. In versions up to and including 26.02.0, a stack buffer overflow occurs during NHML file parsing in `src/filters/dmx_nhml.c`. The value of the xmlHeaderEnd XML attribute is copied from att->value into szXmlHeaderEnd[1000] using strcpy() without any length validation. If the input exceeds 1000 bytes, it overwrites beyond the stack buffer boundary. Commit 9bd7137fded2db40de61a2cf3045812c8741ec52 patches the issue.

Affected products (as reported)

Vendor	Product	Versions
gpac	gpac	<= 26.02.0

Weakness: CWE-121 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P

References

https://github.com/gpac/gpac/security/advisories/GHSA-q7qh-8r2r-q559 x_refsource_CONFIRM
https://github.com/gpac/gpac/commit/9bd7137fded2db40de61a2cf3045812c8741ec52 x_refsource_MISC