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Gpac CVE-2026-27821

HIGH
Stack-based Buffer Overflow (CWE-121)
2026-02-26 security-advisories@github.com
7.8
CVSS 3.1 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
7.8 HIGH
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

4
Analysis Generated
Mar 12, 2026 - 21:55 vuln.today
PoC Detected
Mar 11, 2026 - 23:23 vuln.today
Public exploit code
Patch released
Mar 11, 2026 - 23:23 nvd
Patch available
CVE Published
Feb 26, 2026 - 00:16 nvd
HIGH 7.8

DescriptionGitHub Advisory

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.

AnalysisAI

Stack buffer overflow in GPAC's NHML file parser (versions up to 26.02.0) allows local attackers to achieve code execution by crafting malicious XML files with oversized xmlHeaderEnd attributes that bypass length validation. The vulnerability stems from unsafe use of strcpy() in src/filters/dmx_nhml.c and affects systems processing untrusted NHML files. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Craft malicious NHML file with oversized xmlHeaderEnd attribute
Exploit
Open file in GPAC parser
Execution
Overflow stack buffer via strcpy
Impact
Execute arbitrary code with user privileges

Vulnerability AssessmentAI

Exploitation Attacker must supply a crafted NHML multimedia file with xmlHeaderEnd XML attribute value exceeding 1000 bytes. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment CVSS 7.8 (HIGH). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker could exploit this vulnerability to compromise the affected system.
Remediation A vendor patch is available — apply it immediately. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours: Inventory all systems running GPAC up to version 26.02.0 and assess exposure in production environments. …

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CVE-2026-27821 vulnerability details – vuln.today

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