# CVE-2026-88899: Knowns path traversal in /api/opencode proxy endpoint

Source: https://junglewise.ai/threats/cve-2026-88899-knowns-path-traversal-in-api-opencode-proxy-endpoint  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-10. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-88899 · Severity: critical · CVSS 9.8 · Published 2026-09-10

Knowns is an AI agent platform and project management tool. Versions before 0.31.0 fail to properly validate request headers in an internal proxy endpoint, allowing remote attackers to specify arbitrary directory paths and perform file operations outside the intended project directory on the host system.

Technologies: [Knowns-Dev Knowns](https://junglewise.ai/threats/technologies/knowns). Vendors: [Knowns-Dev](https://junglewise.ai/threats/vendors/knowns-dev).

## Quick answers

**Is CVE-2026-88899 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-88899 being exploited in the wild.

**How severe is CVE-2026-88899?** Critical severity, with a CVSS score of 9.8, published 10 September 2026.

**Which products and versions are affected?** Knowns-Dev Knowns before 0.31.0.

**Is there a fix for CVE-2026-88899?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-88899 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-88899?** Check whether you run Knowns-Dev Knowns at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a path traversal flaw in the /api/opencode proxy endpoint in Knowns versions before 0.31.0. The vulnerable component fails to properly validate the x-opencode-directory request header, allowing attackers to supply arbitrary directory paths. This enables execution of file operations outside the project root on the host system. The endpoint is network-reachable and no authentication is mentioned as a prerequisite. Attackers can exploit this to read, modify, or delete files on the host system. The issue was patched in version 0.31.0 (released 2026-08-19 based on commit context, with public disclosure 2026-09-10).

## Affected products

- knowns-dev Knowns before 0.31.0

## Timeline

- 2026-09-10: disclosed: CVE-2026-88899 published on NVD

## References

- [https://github.com/knowns-dev/knowns/blob/v0.30.0/internal/server/server.go](https://github.com/knowns-dev/knowns/blob/v0.30.0/internal/server/server.go)
- [https://github.com/knowns-dev/knowns/commit/37db0561b37b48b8bd035a417d7f1da6258ae657](https://github.com/knowns-dev/knowns/commit/37db0561b37b48b8bd035a417d7f1da6258ae657)

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