# CVE-2026-75143: FFmpeg Heap Buffer Overflow via RIST Protocol Reader

> A remote attacker can trigger a heap buffer overflow in FFmpeg's RIST protocol reader by sending oversized packets, potentially leading to code execution or crashes.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/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:** 19 Aug 2026
- **Updated:** 27 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-75143, ECHO-a077-2f79-097b, GHSA-7qc3-xqxj-426p, UBUNTU-CVE-2026-75143

## What is CVE-2026-75143?

CVE-2026-75143 is a critical memory corruption vulnerability in FFmpeg, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

FFmpeg before commit 1c10bcc contains a heap buffer overflow in the RIST protocol reader (libavformat/librist.c). librist_read() ignored its size argument and copied the full received payload length into the caller-provided destination buffer, overflowing it when the payload exceeds the destination size. This is reachable via the async:rist:// URL scheme, where the async wrapper supplies a smaller buffer than the received payload. A remote RIST sender can trigger the overflow by sending a packet whose payload exceeds the caller buffer size.

Weakness: CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-75143?


## How do I fix CVE-2026-75143?

Apply the vendor's patch.

## Is CVE-2026-75143 being exploited?

There is no known exploitation of CVE-2026-75143 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-75143 and fix it if it is affected.

What it is: CVE-2026-75143 is a critical memory corruption vulnerability in FFmpeg, published on 19 Aug 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-2026-75143 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-2026-75143/ (Markdown: https://insights.sbomify.com/CVE-2026-75143/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-75143
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-75143
- OSV: https://osv.dev/vulnerability/CVE-2026-75143

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-75143/
Summaries are generated and may contain mistakes; the official description above is the record.