# CVE-2026-58049: FFmpeg - Out-of-Bounds Write in RASC Decoder decode_dlta()

> A crafted media stream triggers an out-of-bounds heap write in FFmpeg's RASC decoder, potentially allowing remote code execution or denial of service.

- **Severity:** High 8.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/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:** Not needed
- **Fix available:** Yes
- **Published:** 28 Jun 2026
- **Updated:** 1 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-58049, ECHO-d121-7767-849c, GHSA-mjxr-6gqf-w78h, JLSEC-2026-1171, UBUNTU-CVE-2026-58049

## What is CVE-2026-58049?

CVE-2026-58049 is a high-severity memory corruption vulnerability in FFmpeg, published on 28 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

FFmpeg's RASC video decoder (decode_dlta in libavcodec/rasc.c) performs 32-bit reads and writes at the row cursor before the NEXT_LINE row-boundary check and validates the DLTA region in pixel rather than byte units, so a DLTA run on a PAL8 frame can access several bytes past the row allocation. A crafted media stream using the RASC FourCC, decoded by libavcodec, triggers a bitstream-controlled out-of-bounds heap write and adjacent out-of-bounds read, leading to memory corruption.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-58049?


## How do I fix CVE-2026-58049?

Apply the vendor's patch.

## Is CVE-2026-58049 being exploited?

There is no known exploitation of CVE-2026-58049 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-58049 and fix it if it is affected.

What it is: CVE-2026-58049 is a high-severity memory corruption vulnerability in FFmpeg, published on 28 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-58049 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-2026-58049/ (Markdown: https://insights.sbomify.com/CVE-2026-58049/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-58049
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-58049
- OSV: https://osv.dev/vulnerability/CVE-2026-58049

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-58049/
Summaries are generated and may contain mistakes; the official description above is the record.