CVE-2026-75146

FFmpeg before commit 65b0dab contains an out-of-bounds read in the DASH demuxer (libavformat/dashdec.c). When a live DASH manifest is refreshed with a startNumber that is lower than the previous value, the current sequence number is driven negative. The fragment retrieval function checked only the upper bound before indexing the fragments array, allowing a negative index to be used and causing an out-of-bounds read. A malicious or misconfigured DASH server can trigger this by serving a live manifest with a decreasing startNumber across a manifest refresh.

Score

CVSS 3.1 8.1 High

Status

Awaiting Analysis - disclosure@vulncheck.com

Published

2026-08-19

Last modified

2026-10-27

Weaknesses

CWE-125

Affected products

• Ffmpeg (Ffmpeg)

References

• https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/65b0dab903e5975e036b30ecc58f5935d4f151e0
• https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24093
• https://www.vulncheck.com/advisories/ffmpeg-out-of-bounds-read-in-dash-demuxer-via-dashdec-c