Executive Summary

[{'type': 'paragraph', 'content': "CVE-2026-4016 is a heap buffer overflow vulnerability in the GPAC multimedia player, specifically in the SVG Parser component's function svgin_process located in src/filters/load_svg.c. The issue arises because an inner size value read from a bitstream overwrites the original packet size used for memory allocation, leading to out-of-bounds read and write operations on a buffer."}, {'type': 'paragraph', 'content': 'This happens when the code reads a 16-bit unsigned integer from the bitstream that is attacker-controlled and much larger than the allocated buffer size. The code then accesses memory beyond the allocated buffer without proper boundary checks, causing heap corruption.'}, {'type': 'paragraph', 'content': 'The vulnerability requires local access to exploit and can cause crashes or potentially allow arbitrary code execution. A patch was released that adds proper boundary checks and preserves the original packet size to prevent out-of-bounds access.'}] [1, 2, 3, 4, 5]

Useful 0 Not Useful 0

Impact Analysis

This vulnerability can impact you by causing memory corruption through out-of-bounds read and write operations, which can lead to Denial of Service (DoS) by crashing the GPAC multimedia player.

More severely, it may allow an attacker with local access to execute arbitrary code, compromising the confidentiality, integrity, and availability of the affected system.

Since the exploit requires local access, remote exploitation is not possible, but local users or malicious software could leverage this flaw to escalate privileges or disrupt system operations.

Applying the provided patch is strongly recommended to mitigate these risks.

Useful 0 Not Useful 0

Compliance Impact

I don't know

Useful 0 Not Useful 0

Detection Guidance

This vulnerability can be detected by testing the GPAC multimedia player with a specially crafted MP4 file that triggers the heap buffer overflow in the svgin_process function. A proof-of-concept (PoC) file named poc_dims_oob.mp4 is available which causes GPAC to crash when processed.

Suggested commands to detect the vulnerability include running GPAC with the PoC file to observe if it crashes or behaves unexpectedly:

• gpac -i poc_dims_oob.mp4 svgplay compositor vout
• gpac -i poc_dims_oob.mp4 -o /dev/null
• gpac -i poc_dims_oob.mp4 inspect

These commands load the crafted MP4 file and will trigger the vulnerability if the system is affected, causing a crash or denial of service.

Useful 0 Not Useful 0

Mitigation Strategies

The immediate mitigation step is to apply the official patch provided by the GPAC project that fixes the buffer overflow in the svgin_process function.

The patch, identified by commit 7618d7206cdeb3c28961dc97ab0ecabaff0c8af2, introduces proper boundary checks and corrects memory allocation to prevent out-of-bounds writes.

Until the patch is applied, avoid processing untrusted or specially crafted SVG or MP4 files that could exploit this vulnerability.

Ensure that only trusted users have local access to the system, as the vulnerability requires local access to be exploited.

Useful 0 Not Useful 0