FFmpeg up to 8.1.2 VobSub subtitle demuxer libavformat/mpeg.c ff_subtitles_queue_insert q heap-based overflow

Summaryinfo

A vulnerability was found in FFmpeg up to 8.1.2. It has been rated as critical. The impacted element is the function ff_subtitles_queue_insert of the file libavformat/mpeg.c of the component VobSub subtitle demuxer. Performing a manipulation of the argument q results in heap-based overflow. This vulnerability is cataloged as CVE-2026-64830. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in FFmpeg up to 8.1.2. It has been classified as critical. This affects the function ff_subtitles_queue_insert of the file libavformat/mpeg.c of the component VobSub subtitle demuxer. The manipulation of the argument q with an unknown input leads to a heap-based overflow vulnerability. CWE is classifying the issue as CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

FFmpeg versions 2.1 through 8.1.2 contains a heap buffer overflow vulnerability in the VobSub subtitle demuxer that allows attackers to corrupt adjacent heap memory by supplying a malicious .sub/.idx subtitle file declaring more distinct stream IDs than the fixed-size array bounds in libavformat/mpeg.c. Attackers can craft a subtitle file with excessive distinct stream IDs to trigger unbounded writes beyond the vobsub->q[] array boundary via ff_subtitles_queue_insert(), potentially achieving arbitrary code execution in any application using FFmpeg's VobSub demuxer.

The advisory is shared at code.ffmpeg.org. This vulnerability is uniquely identified as CVE-2026-64830 since 07/20/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/22/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Multimedia Processing Software

Name

• FFmpeg

Version

• 8.1.0
• 8.1.1
• 8.1.2

License

• open-source

Website

• Product: https://ffmpeg.org/

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