---
title: "HOST-FS-010 /var/tmp Not a Separate Filesystem"
canonical: https://openvapt.com/checks/HOST-FS-010.html
html: https://openvapt.com/checks/HOST-FS-010.html
site: OpenVAPT, https://openvapt.com/
license: OpenVAPT Source-Available Licence 1.3, https://openvapt.com/legal/licence-text.html
modified: 2026-10-14
version: 0.1.0-alpha.6
---

# HOST-FS-010 /var/tmp Not a Separate Filesystem

Checks that /var/tmp is its own mount (or a bind mount of /tmp) with nodev, nosuid and noexec.

- Domain: Server
- Severity: Low
- Control category: Secure Configuration
- Fix effort: medium
- CVSS v3.1 vector: `CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L`
- CIS Controls v8: 4.1
- NIST CSF 2.0: PR.PS-01
- CWE: CWE-276
- NIST SP 800-53 Rev. 5: CM-6, CM-7, SC-5
- Benchmark topic: Separate partitions and mount options (CIS Controls v8 4.1) (topic only, no benchmark text)

## Why It Matters

/var/tmp is world-writable and survives reboots. On the root filesystem it can be filled to exhaust disk space, and it accepts planted device files and executables unless mounted with restricting options.

## How It Detects

Reads /proc/mounts (no command is run) and looks for a mount entry for /var/tmp carrying the options nodev, nosuid, noexec. Unreadable or partial /proc/mounts is reported as incomplete.

## How to Fix

Mount /var/tmp as a separate filesystem, or bind-mount it onto /tmp:  /tmp /var/tmp none bind,nodev,nosuid,noexec 0 0  in /etc/fstab, then reboot or remount. Caution: /var/tmp is meant to survive reboots and some installers and databases run programs from it, so check what uses it before binding it to /tmp with noexec, and keep console access when editing /etc/fstab (a wrong line can stop the boot).

## How to Verify

```
findmnt -no TARGET,OPTIONS /var/tmp
```

## Learn the Theory

- [P1 Linux Server Hardening](https://openvapt.com/academy/p1.md)
- [P17 Kernel, Filesystem and Boot Hardening](https://openvapt.com/academy/p17.md)

## References

- [mount(8), Linux man-pages (nodev, nosuid, noexec)](https://man7.org/linux/man-pages/man8/mount.8.html)
- [proc(5), Linux man-pages (/proc/[pid]/mounts)](https://man7.org/linux/man-pages/man5/proc.5.html)
- [NIST SP 800-123, Guide to General Server Security](https://csrc.nist.gov/pubs/sp/800/123/final)

## Source Code

https://github.com/OpenVAPT/openvapt/blob/574f7f3333c44b75a3c649e2d93a76d507f75adf/internal/checks/host/files_mounts.go

Run it: `openvapt scan --only HOST-FS-010`. Read it offline: `openvapt explain HOST-FS-010`.

---

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