CVE-2026-66065

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.

Severity (CVSS)

Weaknesses

• CWE-15 — CWE-15: External Control of System or Configuration Setting
• CWE-94 — CWE-94: Improper Control of Generation of Code ('Code Injection')

Affected products

References

• https://github.com/Q00/ouroboros/security/advisories/GHSA-jv2h-4p9v-wf5w (x_refsource_CONFIRM)
• https://github.com/Q00/ouroboros/releases/tag/v0.42.1 (x_refsource_MISC)