# CVE-2026-86775: knowns before 0.30.0 Path Traversal via Document API

> Remote attackers can read, write, or delete arbitrary files on the host via path traversal in the Document API, potentially leading to code execution.

- **Severity:** High 8.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** GHSA-3h35-4jq7-hv45, GHSA-h5q7-w9w4-9hcf

## What is CVE-2026-86775?

CVE-2026-86775 is a high-severity path traversal vulnerability in knowns-dev knowns, published on 9 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

knowns (npm package) versions <= 0.29.1 contain a path traversal vulnerability in the Document API. The HTTP handler in internal/server/routes/docs.go normalizes the user-supplied document path with cleanDocPath(), which strips leading/trailing slashes and the .md suffix but does not neutralize ../ traversal sequences, and internal/storage/doc_store.go then builds the target path with filepath.Join(ds.docsDir(), filepath.FromSlash(doc.Path)+".md") without verifying that the resolved path remains inside the documents directory. In the default deployment, where the Management API is unauthenticated and bound to all interfaces, a remote unauthenticated attacker can supply a traversal payload (for example {"path": "../../../../tmp/knowns_pwn_marker"} to POST /api/docs, or an encoded path to GET /api/docs/...) to read, create, overwrite, or delete arbitrary files with a .md extension anywhere on the host filesystem and to create arbitrary directories via os.MkdirAll. This can expose sensitive data stored in other projects' documentation, corrupt or destroy files, and provide an arbitrary-write primitive that may be chained toward code execution. The issue is fixed in version 0.30.0.

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

## Which versions are affected by CVE-2026-86775?


## How do I fix CVE-2026-86775?

No fix has been published for CVE-2026-86775 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86775 being exploited?

There is no known exploitation of CVE-2026-86775 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86775 and fix it if it is affected.

What it is: CVE-2026-86775 is a high-severity path traversal vulnerability in knowns-dev knowns, published on 9 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-86775 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-2026-86775/ (Markdown: https://insights.sbomify.com/CVE-2026-86775/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86775
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86775
- OSV: https://osv.dev/vulnerability/CVE-2026-86775

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86775/
Summaries are generated and may contain mistakes; the official description above is the record.