CVE-2026-64830: ffmpeg Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-64830 is a high (CVSS 8.8) Heap-based Buffer Overflow vulnerability in ffmpeg. EPSS estimates a 0.65% chance of exploitation in the next 30 days, higher than 49.9% of scored vulnerabilities.

Timeline

1. 22-07-2026
   PublishedVulnerability first disclosed.
2. 28-07-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-122Heap-based Buffer OverflowA 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().