# CVE-2026-88899

## Summary

- **CVE ID:** CVE-2026-88899
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-73
- **Published:** Sep 10, 2026
- **Last Modified:** Sep 10, 2026

## Description

knowns versions before 0.31.0 fail to properly validate the x-opencode-directory request header in the /api/opencode proxy endpoint. Remote attackers can supply arbitrary directory paths to execute file operations outside the project root on the host system.

## Affected Products

- knowns-dev — knowns (0)
- knowns-dev — knowns (0.31.0)

## References

- [CNA](https://github.com/knowns-dev/knowns/security/advisories/GHSA-9h2q-r9fh-f98w)
- [CNA](https://github.com/knowns-dev/knowns/blob/v0.30.0/internal/server/server.go#L1283-L1296)
- [CNA](https://github.com/knowns-dev/knowns/commit/37db0561b37b48b8bd035a417d7f1da6258ae657)
- [CNA](https://github.com/knowns-dev/knowns/releases/tag/v0.31.0)
- [CNA](https://www.vulncheck.com/advisories/knowns-before-0.31.0-external-control-of-agent-working-directory-via-x-opencode-directory-header)

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._