CVE-2017-18078 — systemd-tmpfiles in systemd before 237 attempts to support ownership/permission

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 whi

01What is this vulnerability?

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.

02Affected products

Vendor	Product	Versions
n	a / n/a	n/a

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2018-01-29T05:00:00.000Z
• Last modified: 2024-08-05T21:13:47.523Z

09References

• lists.opensuse.org — http://lists.opensuse.org/opensuse-updates/2018-02/msg00109.html
• www.openwall.com — http://www.openwall.com/lists/oss-security/2018/01/29/3
• www.exploit-db.com — https://www.exploit-db.com/exploits/43935/
• github.com — https://github.com/systemd/systemd/issues/7736
• packetstormsecurity.com — http://packetstormsecurity.com/files/146184/systemd-Local-Privilege-Escalation.h…
• www.openwall.com — https://www.openwall.com/lists/oss-security/2018/01/29/4
• lists.debian.org — https://lists.debian.org/debian-lts-announce/2019/04/msg00022.html
• lists.apache.org — https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8…
• lists.apache.org — https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e3…