CVE-2018-6954: canonical ubuntu_linux
Vulnerability summary
CVE-2018-6954 is a high (CVSS 7.8) vulnerability in canonical ubuntu_linux. EPSS estimates a 0.53% chance of exploitation in the next 30 days, higher than 44.6% of scored vulnerabilities. 1 public exploit is recorded.
Public exploit (GitHub, Date unknown)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 5 · Related 6Timeline
- 13-02-2018PublishedVulnerability first disclosed.
- 09-06-2025Last modifiedVulnerability information updated.
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.
CVSS metrics
7 scores · 5 sources · 3 versions- NVDNIST7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- OSV · UbuntuEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- OSV · ChainguardEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.53%
Chance of exploitation in the next 30 days
Percentile
45%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.53% on 05-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
1 foundSystemd
Maturity: poc
Weaknesses
CWE · root causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Chainguard5 products
- py3-systemdAll versions (No fix recorded)
- py3.10-systemdAll versions (No fix recorded)
- py3.11-systemdAll versions (No fix recorded)
- py3.12-systemdAll versions (No fix recorded)
- py3.13-systemdAll versions (No fix recorded)
Canonical1 product
- ubuntu_linuxEOL16.04 | 18.04 | 18.10
Debian1 product
- systemd< 238-1
Opensuse1 product
- leapEOL42.3
Systemd_project1 product
- systemd≤ 237
Ubuntu1 product
- systemd< 229-4ubuntu21.15 | < 229-4ubuntu21.9 | < 237-3ubuntu10.9
6 vendors · 10 products
References
11 links- github.com/systemd/systemd/issues/7986X Refsource MISCExploitIssue TrackingPatchThird Party AdvisoryFIX
- lists.opensuse.org/opensuse-security-announce/2019-05/msg00062.htmlVendor AdvisoryX Refsource SUSEThird Party AdvisoryAdvisory
