{"affected":[{"product":"heym","source":"CNA: GitHub_M","vendor":"heymrun","versions":[{"status":"affected","version":"< 0.0.75"}]}],"cveId":"CVE-2026-67546","cwes":["CWE-94"],"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.","epss":null,"exploits":[],"kev":null,"metrics":[{"score":8.8,"severity":"high","source":"CNA: GitHub_M","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}],"modifiedAt":1794433263020,"publishedAt":1794433263020,"references":[{"source":"CNA: GitHub_M","tags":["x_refsource_CONFIRM"],"url":"https://github.com/heymrun/heym/security/advisories/GHSA-378x-q589-34mv"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/heymrun/heym/commit/22b8ee60eb92128cf4ff04a9b6c0e1b62bf25a01"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/heymrun/heym/commit/6c6213f88dfa8b2a70d23a9a271171241e910904"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/heymrun/heym/releases/tag/v0.0.75"}],"remediation":[],"revision":"b21565d3e77480377f2d52547aff07f2d46f3054b324b1cc8af3c0449fd2e6da","sources":[{"modifiedAt":1794433263020,"name":"CNA: GitHub_M","retrievedAt":1794435082348,"url":"https://www.cve.org/CVERecord?id=CVE-2026-67546"}],"ssvc":null,"status":"published","title":"Heym: Command execution via POST /api/mcp/fetch-tools stdio transport: supplied command is spawned before MCP validation","updatedAt":1794435082348}