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Fencer Intel
high 7.8

CVE-2018-6954 json

systemd-tmpfiles in systemd through 237 mishandles symlinks present in non-terminal path components, which allows local users to obtain own…

published 8y ago modified 4mo ago also EUVD-2018-18698

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

systemd-tmpfiles in systemd through 237 mishandles symlinks present in non-terminal path components, which allows local users to obtain ownership of arbitrary files via vectors involving creation of a directory and a file under that directory, and later replacing that directory with a symlink. This occurs even if the fs.protected_symlinks sysctl is turned on.

Patch / fix

  • systemd Debian 14, Debian 13, Debian 12 238-1

debian advisories DEBIAN-CVE-2018-6954

  • systemd Ubuntu 16.04 LTS 229-4ubuntu21.15
  • systemd Ubuntu 18.04 LTS 237-3ubuntu10.9

ubuntu advisories UBUNTU-CVE-2018-6954

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • systemd SLES for SAP 12 SP4, SLES for SAP 12 SP3, SLES for SAP 12 SP2 +10 more 228-150.66.4
  • systemd SLE Module for Basesystem 15 234-24.20.1

suse advisories SUSE-SU-2019:1265-1SUSE-SU-2019:0137-1

  • systemd openSUSE Tumbleweed 249.4-2.2
  • systemd openSUSE Leap 15.0 234-lp150.20.12.1
  • systemd-mini openSUSE Leap 15.0 234-lp150.20.12.1

opensuse advisories openSUSE-SU-2024:11420-1openSUSE-SU-2019:0098-1

  • systemd Arch Linux 240.0-3

arch linux advisories AVG-615

Is CVE-2018-6954 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2018-6954 updated cvss 7.0

systemd: Mishandled symlinks in systemd-tmpfiles allows local users to obtain ownership of arbitrary files

  • Red Hat Enterprise Linux 7 systemd, libgudev1, systemd-libs, systemd-sysv, systemd-python, systemd-networkd, +2 more
    affected: workaround, no fix planned “There is no known mitigation available.”
  • Red Hat Enterprise Linux 8 systemd, systemd-pam, systemd-libs, systemd-udev, systemd-tests, systemd-container, +1 more
    not affected: vulnerable code not present

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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
last yr.

Exploit prediction

0.53% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/systemd/systemd/issues/7986 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA 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 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C

Classification

Weakness
  • CWE-59 Improper Link Resolution Before File Access

References

Sources

Fencer Intel 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.