Vulnerability · Published Aug 19, 2026 · Assigned by VulnCheck

CVE-2026-75146FFmpeg Out-of-Bounds Read in DASH Demuxer via dashdec.c

High 8.1

In plain English

A high-severity out-of-bounds read in FFmpeg from FFmpeg. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.1High

Exploit odds (30 days)0.3%top 82.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	ffmpeg	no fix listed	DEBIAN-CVE-2026-75146
Debian:13	ffmpeg	no fix listed	DEBIAN-CVE-2026-75146
Debian:14	ffmpeg	7:9.0.2-1	DEBIAN-CVE-2026-75146
Ubuntu:26.10	ffmpeg	no fix listed	UBUNTU-CVE-2026-75146

Affected products (as reported)

Vendor	Product	Versions
FFmpeg	FFmpeg	0 – before 65b0dab903e5975e036b30ecc58f5935d4f151e0

Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

References

Pull Request issue-tracking
Patch Commit patch
https://www.vulncheck.com/advisories/ffmpeg-out-of-bounds-read-in-dash-demuxer-via-dashdec-c third-party-advisory