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.
History

Fri, 13 Nov 2026 07:45:00 +0000

Type Values Removed Values Added
First Time appeared Heymrun
Heymrun heym
Vendors & Products Heymrun
Heymrun heym

Wed, 11 Nov 2026 21:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Heym: Command execution via POST /api/mcp/fetch-tools stdio transport: supplied command is spawned before MCP validation
Weaknesses CWE-94
References
Metrics cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-11-11T21:41:03.020Z

Updated: 2026-11-12T17:54:44.721Z

Reserved: 2026-07-29T18:47:17.074Z

Link: CVE-2026-67546

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-11-11T22:17:29.533

Modified: 2026-11-12T18:17:52.973

Link: CVE-2026-67546

cve-icon Redhat

No data.