CVE-2026-75146 FFmpeg Out-of-Bounds Read in DASH Demuxer via dashdec.c
A malicious DASH server can trigger an out-of-bounds read in FFmpeg by manipulating manifest start numbers, potentially causing crashes or data leaks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-75146?
CVE-2026-75146 is a high-severity memory corruption vulnerability in FFmpeg, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
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.
Weakness: CWE-125
Which versions are affected by CVE-2026-75146?
How do I fix CVE-2026-75146?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-75146 being exploited?
There is no known exploitation of CVE-2026-75146 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-75146, ECHO-95fc-7da4-df04, GHSA-564v-jr2q-mgwf, UBUNTU-CVE-2026-75146.