# CVE-2017-18078: Privilege escalation in n/a

> Local attackers can bypass access restrictions and modify file ownership, such as /etc/passwd, if protected hardlinks are disabled.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Jan 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2017-18078, GHSA-g2wx-phqf-j84q, SUSE-SU-2018:0546-1, UBUNTU-CVE-2017-18078

## What is CVE-2017-18078?

CVE-2017-18078 is a high-severity vulnerability in Debian Debian Linux, published on 29 Jan 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-59 (Improper Link Resolution Before File Access)

## Which versions are affected by CVE-2017-18078?

It affects 3 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `systemd` | SUSE:Linux Enterprise Desktop 12 SP2 | All versions | 228-150.32.1 |
| `systemd` | SUSE:Linux Enterprise Desktop 12 SP3 | All versions | 228-150.32.1 |
| `systemd` | SUSE:Linux Enterprise Server 12 SP2 | All versions | 228-150.32.1 |
| `systemd` | SUSE:Linux Enterprise Server 12 SP3 | All versions | 228-150.32.1 |
| `systemd` | SUSE:Linux Enterprise Server for Raspberry Pi 12 SP2 | All versions | 228-150.32.1 |
| `systemd` | SUSE:Linux Enterprise Server for SAP Applications 12 SP2 | All versions | 228-150.32.1 |
| `systemd` | SUSE:Linux Enterprise Server for SAP Applications 12 SP3 | All versions | 228-150.32.1 |
| `systemd` | SUSE:Linux Enterprise Software Development Kit 12 SP2 | All versions | 228-150.32.1 |
| `systemd` | SUSE:Linux Enterprise Software Development Kit 12 SP3 | All versions | 228-150.32.1 |

Products: Debian Debian Linux, Opensuse Leap, Systemd Project Systemd.

## How do I fix CVE-2017-18078?

Upgrade to a fixed version.

## Is CVE-2017-18078 being exploited?

There is no known exploitation of CVE-2017-18078 in the wild and no public exploit code.

Public exploit code:

- systemd (systemd-tmpfiles) < 236 - 'fs.protected_hardlinks=0' Local Privilege Escalation (exploitdb)

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-18078 and fix it if it is affected.

What it is: CVE-2017-18078 is a high-severity vulnerability in Debian Debian Linux, published on 29 Jan 2018. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2017-18078 in the wild and no public exploit code.

Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2017-18078/ (Markdown: https://insights.sbomify.com/CVE-2017-18078/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-18078
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-18078
- OSV: https://osv.dev/vulnerability/CVE-2017-18078

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-18078/
Summaries are generated and may contain mistakes; the official description above is the record.