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Fencer Vulns
high 7.8

CVE-2017-18078 json

systemd-tmpfiles in systemd before 237 attempts to support ownership/permission changes on hardlinked files even if the fs.protected_hardli…

published 2018-01-29 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-9215

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 64%
public exploits
1
Exploit-DB

Summary

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.

Patch / fix

  • systemd_project systemd 237
  • systemd Debian 14, Debian 13, Debian 12 237-1

debian advisories DEBIAN-CVE-2017-18078

  • systemd SLES for SAP 12 SP3, SLES for SAP 12 SP2, SLES for Raspberry Pi 12 SP2 +6 more 228-150.32.1

suse advisories SUSE-SU-2018:0546-1

  • systemd openSUSE Tumbleweed 249.4-2.2

opensuse advisories openSUSE-SU-2024:11420-1

  • systemd Arch Linux 237.0-1

arch linux advisories AVG-621

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2017-18078 updated cvss 6.7

systemd: Unsafe handling of hard links allowing privilege escalation

  • Red Hat Enterprise Linux 7 systemd, libgudev1, systemd-libs, systemd-sysv, systemd-python, systemd-networkd, +2 more
    affected: workaround, no fix planned “Will not fix”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. First public exploit (EDB-43935)
  2. Published

Exploit prediction

1.06% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-43935 systemd (systemd-tmpfiles) < 236 - 'fs.protected_hardlinks=0' Local Privilege Escalation local, 2018-01-29
  • openwall.com http://www.openwall.com/lists/oss-security/2018/01/29/3 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/systemd/systemd/issues/7736 referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/146184/systemd-Local-Privilege-Escalation.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 4.6 AV:L/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-59 Improper Link Resolution Before File Access

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.