Description
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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | systemd | 237-1 | — |
| Debian 13 | systemd | 237-1 | — |
| Debian 12 | systemd | 237-1 | — |
| Debian 8 | systemd | 215-17+deb8u12 | DLA-1762-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | systemd | No fix yet | — |
| Ubuntu Pro 14.04 LTS | systemd | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | systemd | 228-150.32.1 | SUSE-SU-2018:0546-1 |
| SLES 12 SP2 | systemd | 228-150.32.1 | SUSE-SU-2018:0546-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP3 | systemd | 228-150.32.1 | SUSE-SU-2018:0546-1 |
| SLES for SAP 12 SP2 | systemd | 228-150.32.1 | SUSE-SU-2018:0546-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | systemd | 249.4-2.2 | openSUSE-SU-2024:11420-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Exploit-DB 1
- systemd (systemd-tmpfiles) < 236 - 'fs.protected_hardlinks=0' Local Privilege Escalation EDB-43935 · local · Jan 29, 2018
GitHub 1 repository
-
federiconbaez/cortex9-tmpfiles-hardlink-chown-race-model ★ 0 · Nov 6, 2026
Limited educational in-memory FS model of systemd-tmpfiles path_set_perms vs hardlinks (CVE-2017-18078). Not a finding; no real files.
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 3
- DLA-1762-1 systemd - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2018:0546-1 Security update for systemd SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:11420-1 libsystemd0-249.4-2.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- openSUSE-SU-2018:0560 vendor-advisory
- [oss-security] 20180129 CVE-2018-18078: systemd-tmpfiles root privilege escalation with fs.protected_hardlinks=0 mailing-list
- 43935 exploit
- https://github.com/systemd/systemd/issues/7736
- http://packetstormsecurity.com/files/146184/systemd-Local-Privilege-Escalation.html
- [oss-security] 20180129 Re: CVE-2017-18078: systemd-tmpfiles root privilege mailing-list
- [debian-lts-announce] 20190424 [SECURITY] [DLA 1762-1] systemd security update mailing-list
- [bookkeeper-issues] 20210628 [GitHub] [bookkeeper] padma81 opened a new issue #2746: Security Vulnerabilities in CentOS 7 image, Upgrade image to CentOS 8 mailing-list
- [bookkeeper-issues] 20210629 [GitHub] [bookkeeper] padma81 opened a new issue #2746: Security Vulnerabilities in CentOS 7 image, Upgrade image to CentOS 8 mailing-list