CVE-2018-6954

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2018-02-13 · updated 2026-06-17
Weakness: CWE-59

Description

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.

Affected products

Canonical Ubuntu Linux: 16.04, 18.04, 18.10
openSUSE Leap: 42.3
systemd: through 237

References

http://lists.opensuse.org/opensuse-security-announce/2019-05/msg00062.html
https://github.com/systemd/systemd/issues/7986
https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
https://usn.ubuntu.com/3816-1/
https://usn.ubuntu.com/3816-2/
http://lists.opensuse.org/opensuse-security-announce/2019-05/msg00062.html
https://github.com/systemd/systemd/issues/7986
https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
https://usn.ubuntu.com/3816-1/
https://usn.ubuntu.com/3816-2/

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