CVE-2026-1418: Gpac Buffer Overflow Vulnerability

CVE-2026-1418 Overview

A security vulnerability has been identified in GPAC, the open-source multimedia framework, affecting versions up to 2.4.0. The vulnerability exists in the gf_text_import_srt_bifs function within the file src/scene_manager/text_to_bifs.c, which is part of the SRT Subtitle Import component. This out-of-bounds write vulnerability can be exploited through manipulation of SRT subtitle files, potentially allowing an attacker to corrupt memory and destabilize the application.

Critical Impact

Local attackers with low privileges can exploit this out-of-bounds write vulnerability in GPAC's SRT subtitle import functionality to potentially corrupt memory, leading to application crashes or arbitrary code execution in the context of the running process.

Affected Products

• GPAC versions up to and including 2.4.0
• Systems using GPAC for multimedia processing with SRT subtitle support
• Applications integrating the GPAC library for subtitle handling

Discovery Timeline

• 2026-01-26 - CVE-2026-1418 published to NVD
• 2026-01-28 - Last updated in NVD database

Technical Details for CVE-2026-1418

Vulnerability Analysis

This vulnerability is classified as an out-of-bounds write (CWE-787) and improper restriction of operations within the bounds of a memory buffer (CWE-119). The flaw resides in the gf_text_import_srt_bifs function, which is responsible for processing SRT subtitle files and converting them to BIFS (Binary Format for Scenes) format.

When handling malformed or specially crafted SRT subtitle input, the function fails to properly validate buffer boundaries before performing write operations. This allows data to be written outside the allocated memory region, potentially overwriting adjacent memory structures. The attack requires local access to the system and the ability to provide a malicious SRT file to the GPAC application for processing.

Root Cause

The root cause of this vulnerability stems from insufficient bounds checking in the SRT subtitle parsing logic within text_to_bifs.c. When the gf_text_import_srt_bifs function processes subtitle data, it does not adequately verify that the destination buffer has sufficient capacity to hold the incoming data, leading to memory corruption when oversized or malformed input is provided.

Attack Vector

The attack requires local access where an attacker must provide a malicious SRT subtitle file to be processed by an application using the vulnerable GPAC library. The exploit has been publicly disclosed through the GitHub issue tracker. Successful exploitation could result in:

1. Application crash (denial of service)
2. Memory corruption affecting application stability
3. Potential arbitrary code execution if the attacker can control the out-of-bounds write location and data

  *			GPAC - Multimedia Framework C SDK
  *
  *			Authors: Jean Le Feuvre
- *			Copyright (c) Telecom ParisTech 2000-2023
+ *			Copyright (c) Telecom ParisTech 2000-2026
  *				All rights reserved
  *
  *  This file is part of GPAC / Scene Management sub-project

Source: GitHub Commit

Detection Methods for CVE-2026-1418

Indicators of Compromise

• Unexpected crashes in applications using GPAC when processing SRT subtitle files
• Memory access violations or segmentation faults during subtitle import operations
• Suspicious SRT files with abnormally large or malformed content being processed
• Core dumps or crash logs referencing gf_text_import_srt_bifs or text_to_bifs.c

Detection Strategies

• Monitor for application crashes in GPAC-based processes, particularly those involving subtitle processing
• Implement file integrity checks on SRT files before processing with GPAC
• Use memory sanitizers (AddressSanitizer, Valgrind) in development and testing environments to detect out-of-bounds writes
• Deploy endpoint detection solutions capable of identifying memory corruption attempts

Monitoring Recommendations

• Enable crash reporting for applications using the GPAC library
• Monitor system logs for abnormal process terminations related to multimedia processing
• Implement input validation logging for subtitle file processing operations
• Track file access patterns for SRT files, particularly from untrusted sources

How to Mitigate CVE-2026-1418

Immediate Actions Required

• Update GPAC to a version that includes patch 10c73b82cf0e367383d091db38566a0e4fe71772
• Restrict processing of SRT subtitle files from untrusted sources
• Implement input validation for subtitle files before passing them to GPAC
• Consider sandboxing GPAC-based applications to limit the impact of potential exploitation

Patch Information

A security patch has been made available addressing this vulnerability. The fix is identified by commit hash 10c73b82cf0e367383d091db38566a0e4fe71772. Users should apply this patch or upgrade to a patched version of GPAC as soon as possible. The patch details can be found in the GitHub Commit Update and additional context is available in the GitHub Issue Tracker.

Workarounds

• Disable SRT subtitle import functionality if not required for your use case
• Implement strict input validation and sanitization for all subtitle files before processing
• Run GPAC-based applications with reduced privileges to minimize the impact of potential exploitation
• Use application sandboxing or containerization to isolate GPAC processes from critical system resources

# Example: Building GPAC with the security patch applied
git clone https://github.com/gpac/gpac.git
cd gpac
git fetch origin
git cherry-pick 10c73b82cf0e367383d091db38566a0e4fe71772
./configure
make
sudo make install