# CVE-2026-53581: ntp: write path traversal

> An attacker with NTP configuration access can overwrite arbitrary files as root via path traversal in the GPS/PPS parameter, leading to code execution.

- **Severity:** Critical 9.0 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Sep 2026
- **Updated:** 9 Sep 2026
- **Also known as:** GHSA-872g-g543-j37m

## What is CVE-2026-53581?

CVE-2026-53581 is a critical path traversal vulnerability in opnsense core, published on 8 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.9 of opnsense/core and version 26.4_20 of BE/opnsense/core, a path traversal vulnerability in the NTP configuration module allows an attacker to overwrite arbitrary files on the system as the root user. By manipulating the GPS or PPS serial port parameter, an attacker with access to the NTP configuration can escape the intended directory and force the system to write user-controlled data to any file on the filesystem. Version 26.1.9 of opnsense/core and version 26.4_20 of BE/opnsense/core patch the issue.

Weakness: CWE-73 (External Control of File Name or Path), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-53581?


## How do I fix CVE-2026-53581?

No fix has been published for CVE-2026-53581 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-53581 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53581 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53581 and fix it if it is affected.

What it is: CVE-2026-53581 is a critical path traversal vulnerability in opnsense core, published on 8 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53581 exists.

Affected product: opnsense core. 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-2026-53581/ (Markdown: https://insights.sbomify.com/CVE-2026-53581/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53581
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53581
- OSV: https://osv.dev/vulnerability/CVE-2026-53581

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53581/
Summaries are generated and may contain mistakes; the official description above is the record.