# CVE-2026-86541: knowns before 0.30.0 Path Traversal via code.replace MCP action

> Attackers can overwrite arbitrary files outside the project root via path traversal in the code.replace action, potentially leading to code execution.

- **Severity:** High 7.2 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 7 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-f539-xgc6-xw7q, GHSA-g6q2-h5cf-8q26

## What is CVE-2026-86541?

CVE-2026-86541 is a high-severity path traversal vulnerability in knowns-dev knowns, published on 7 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

knowns versions before 0.30.0 contain a path traversal vulnerability in the handleCodeReplace() function that allows attackers to overwrite arbitrary files outside the project root. Attackers can supply absolute paths or relative paths containing directory traversal sequences to write malicious content to sensitive files like shell startup scripts or SSH configuration files.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-86541?


## How do I fix CVE-2026-86541?

No fix has been published for CVE-2026-86541 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86541 being exploited?

There is no known exploitation of CVE-2026-86541 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86541 and fix it if it is affected.

What it is: CVE-2026-86541 is a high-severity path traversal vulnerability in knowns-dev knowns, published on 7 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-86541 in the wild and no public exploit code.

Affected product: knowns-dev knowns. 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-2026-86541/ (Markdown: https://insights.sbomify.com/CVE-2026-86541/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86541
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86541
- OSV: https://osv.dev/vulnerability/CVE-2026-86541

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86541/
Summaries are generated and may contain mistakes; the official description above is the record.