# 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.

- **Severity:** High 7.2 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **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:** Yes
- **Published:** 19 Aug 2026
- **Updated:** 27 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-75146, ECHO-95fc-7da4-df04, GHSA-564v-jr2q-mgwf, UBUNTU-CVE-2026-75146

## 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 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-75146?


## How do I fix CVE-2026-75146?

Apply the vendor's patch.

## Is CVE-2026-75146 being exploited?

There is no known exploitation of CVE-2026-75146 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-75146 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-75146 in the wild and no public exploit code.

Affected product: FFmpeg. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-75146/ (Markdown: https://insights.sbomify.com/CVE-2026-75146/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-75146
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-75146
- OSV: https://osv.dev/vulnerability/CVE-2026-75146

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-75146/
Summaries are generated and may contain mistakes; the official description above is the record.