CVE-2025-0518: FFmpeg Buffer Overflow Vulnerability

CVE-2025-0518 Overview

CVE-2025-0518 is an Unchecked Return Value and Out-of-bounds Read vulnerability affecting FFmpeg, the widely-used multimedia processing framework. The vulnerability exists in the audio filter component, specifically within libavfilter/af_pan.c, where improper handling of sscanf() return values can lead to reading sensitive memory contents. This flaw allows attackers to potentially read sensitive constants within the executable when processing specially crafted media files.

Critical Impact

This vulnerability enables attackers to potentially access sensitive memory contents through crafted media files processed by FFmpeg, leading to information disclosure.

Affected Products

• FFmpeg version 7.1
• Applications and services that integrate FFmpeg 7.1 for media processing
• Debian-based systems using vulnerable FFmpeg packages

Discovery Timeline

• 2025-01-16 - CVE-2025-0518 published to NVD
• 2025-11-03 - Last updated in NVD database

This vulnerability was discovered by Simcha Kosman.

Technical Details for CVE-2025-0518

Vulnerability Analysis

The vulnerability resides in the af_pan.c audio filter within FFmpeg's libavfilter library. The core issue stems from improper validation of the sscanf() function's return value when parsing audio channel gain parameters. The sscanf() function returns the number of input items successfully matched and assigned, but the original code did not properly check this return value before proceeding to use the parsed data.

When the return value is not properly validated, the code may continue execution with uninitialized or stale values in the gain variable, potentially leading to out-of-bounds read operations. This can expose sensitive memory contents that should not be accessible during normal operation.

Root Cause

The root cause is an unchecked return value from the sscanf() function in the pan audio filter. The vulnerable code path uses the result of sscanf() without verifying that at least one value was successfully parsed. According to CWE-125 (Out-of-bounds Read), this type of vulnerability occurs when the software reads data past the end of the intended buffer, which can result in reading sensitive information from other memory locations.

Attack Vector

The attack vector is network-based, requiring an attacker to deliver a maliciously crafted media file to a target system running FFmpeg 7.1. The attack requires:

1. A victim to process a specially crafted media file using FFmpeg
2. The media file must trigger the vulnerable pan audio filter code path
3. User interaction is required to initiate the media processing

The exploitation could occur through various scenarios including media streaming services, file conversion utilities, or any application that uses FFmpeg for audio processing.

         sign = 1;
         while (1) {
             gain = 1;
-            if (sscanf(arg, "%lf%n *%n", &gain, &len, &len))
+            if (sscanf(arg, "%lf%n *%n", &gain, &len, &len) >= 1)
                 arg += len;
             if (parse_channel_name(&arg, &in_ch_id, &named)){
                 av_log(ctx, AV_LOG_ERROR,

Source: GitHub FFmpeg Commit

The fix ensures that the sscanf() return value is properly validated by checking that at least one field was successfully parsed (>= 1) before proceeding with the parsed data.

Detection Methods for CVE-2025-0518

Indicators of Compromise

• Unexpected crashes or memory access errors in FFmpeg when processing audio files
• Abnormal memory access patterns in processes utilizing FFmpeg's pan audio filter
• Error logs showing parsing failures in af_pan.c component
• Unusual information leakage during media file processing operations

Detection Strategies

• Monitor FFmpeg process behavior for signs of memory disclosure or abnormal termination
• Implement file integrity monitoring on FFmpeg binaries to detect tampering
• Deploy runtime application self-protection (RASP) solutions to detect out-of-bounds read attempts
• Use SentinelOne's behavioral AI to identify anomalous media processing activities

Monitoring Recommendations

• Enable detailed logging for FFmpeg operations, particularly audio filter processing
• Implement network monitoring to detect potentially malicious media file transfers
• Configure alerts for FFmpeg processes exhibiting unusual memory access patterns
• Monitor for exploitation attempts targeting media processing pipelines

How to Mitigate CVE-2025-0518

Immediate Actions Required

• Update FFmpeg to a patched version that includes commit b5b6391d64807578ab872dc58fb8aa621dcfc38a
• Review and audit all systems using FFmpeg 7.1 for potential exposure
• Implement input validation for media files before FFmpeg processing
• Consider isolating FFmpeg processing in sandboxed environments

Patch Information

The vulnerability has been addressed in the official FFmpeg repository. The fix is available in commit b5b6391d64807578ab872dc58fb8aa621dcfc38a. Organizations should apply this patch immediately or upgrade to a version that includes this fix.

For Debian-based systems, refer to the Debian LTS Announcement for package update information.

Workarounds

• Disable the pan audio filter if not required for your use case
• Implement strict input validation and sanitization for all media files processed by FFmpeg
• Process untrusted media files in isolated, sandboxed environments with limited privileges
• Consider using alternative audio processing solutions until FFmpeg is updated

# Verify FFmpeg version and check if patch is applied
ffmpeg -version

# For Debian-based systems, update FFmpeg packages
sudo apt update && sudo apt upgrade ffmpeg

# Verify the patched version is installed
dpkg -l | grep ffmpeg