CVE-2026-67546

CVSS 8.8 (high) · published 2026-11-11

Heym builds and runs agentic systems and business-process automations on self-hosted infrastructure. Prior to version 0.0.75, the same POST /api/mcp/fetch-tools endpoint (any authenticated user, lowest role) also accepts the stdio transport, which spawns the attacker-supplied command with attacker-supplied args and an environment merged over os.environ. The process executes on the shared backend host before MCP protocol validation fails — so side effects fire regardless of whether the command speaks MCP. This is a distinct weakness class and exploit primitive from the SSRF (Advisory 2) on the same endpoint, and needs a different fix (role gating / opt-in trust boundary rather than egress controls). This issue has been patched in version 0.0.75.

Weakness: CWE-94

Source: NVD CVE-2026-67546

References

• https://github.com/heymrun/heym/commit/22b8ee60eb92128cf4ff04a9b6c0e1b62bf25a01
• https://github.com/heymrun/heym/commit/6c6213f88dfa8b2a70d23a9a271171241e910904
• https://github.com/heymrun/heym/releases/tag/v0.0.75
• https://github.com/heymrun/heym/security/advisories/GHSA-378x-q589-34mv

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