# CVE-2026-66065

## Summary

- **CVE ID:** CVE-2026-66065
- **Severity:** HIGH
- **CVSS Score:** 8.4 (CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-15, CWE-94
- **Published:** Aug 3, 2026
- **Last Modified:** Aug 5, 2026

## Description

Ouroboros is a local-first runtime for AI coding agents that records their actions and applies user-defined policies to constrain behavior. Versions prior to 0.42.1 have an incomplete denylist. Several execution-routing keys of the same RCE class were omitted, so a malicious cloned repo can still reach arbitrary command execution by shipping a .env (auto-loaded at import, with no review step). The CVE-2026-47211 fix added _UNTRUSTED_ENV_DENYLIST to stop an untrusted project-directory .env from redirecting execution, but it did not account for all keys. The backend config-home and MCP/plugin roots bypass the approval gate by pointing the nested agent, MCP servers, and plugin roster at attacker config. Other variables re-enable blocked local transports, replace sub-agent prompts, switch backends, and lower tool approval classes, further weakening the approval gate. This issue has been fixed in version 0.42.1.

## Affected Products

- Q00 — ouroboros (< 0.42.1)

## References

- [CNA](https://github.com/Q00/ouroboros/security/advisories/GHSA-jv2h-4p9v-wf5w)
- [CNA](https://github.com/Q00/ouroboros/releases/tag/v0.42.1)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.30%
- **EPSS Percentile:** 22.0

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