{"id":"CVE-2026-67546","summary":"Heym: Command execution via POST /api/mcp/fetch-tools stdio transport: supplied command is spawned before MCP validation","details":"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.","aliases":["GHSA-378x-q589-34mv"],"modified":"2026-11-12T10:45:39.366156474Z","published":"2026-11-11T21:41:03.020Z","database_specific":{"cwe_ids":["CWE-94"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/67xxx/CVE-2026-67546.json","cna_assigner":"GitHub_M"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/67xxx/CVE-2026-67546.json"},{"type":"FIX","url":"https://github.com/heymrun/heym/commit/22b8ee60eb92128cf4ff04a9b6c0e1b62bf25a01"},{"type":"FIX","url":"https://github.com/heymrun/heym/commit/6c6213f88dfa8b2a70d23a9a271171241e910904"},{"type":"WEB","url":"https://github.com/heymrun/heym/releases/tag/v0.0.75"},{"type":"ADVISORY","url":"https://github.com/heymrun/heym/security/advisories/GHSA-378x-q589-34mv"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-67546"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/heymrun/heym","events":[{"introduced":"0"},{"fixed":"6c6213f88dfa8b2a70d23a9a271171241e910904"},{"fixed":"22b8ee60eb92128cf4ff04a9b6c0e1b62bf25a01"}],"database_specific":{"extracted_events":[{"range":[{"introduced":"0"},{"fixed":"0.0.75"}],"source":"AFFECTED_FIELD","strategy":"StringRangeExpression"},{"range":[{"fixed":"22b8ee60eb92128cf4ff04a9b6c0e1b62bf25a01"}],"source":"REFERENCES_COMMIT"},{"range":[{"fixed":"6c6213f88dfa8b2a70d23a9a271171241e910904"}],"source":"REFERENCES_COMMIT"},{"source":"REFERENCES_TAG","original_tag":"v0.0.75","range":[{"fixed":"6c6213f88dfa8b2a70d23a9a271171241e910904"}]}]}}],"versions":["v0.0.74","0.0.73","v0.0.72","opencode-pr-assets","0.0.71","codex-pr-assets","0.0.70","v0.0.69","v0.0.68","v0.0.67","v0.0.66","v0.0.65","v0.0.64","v0.0.63","v0.0.62","v0.0.61","v0.0.60","v0.0.59","v0.0.58","v0.0.57","v0.0.56","v0.0.55","v0.0.54","v0.0.53","v0.0.52","v0.0.51","v0.0.50","v.0.0.49","v0.0.48","v0.0.47","v0.0.46","v0.0.45","v0.0.44","v0.0.43","v0.0.42","v0.0.41","v0.0.40","v0.0.39","v0.0.38","v0.0.37","v0.0.36","v0.0.35","v0.0.34","v0.0.33","v0.0.32","v0.0.31","v0.0.30","v0.0.29","v0.0.27","v0.0.26","v0.0.25","v0.0.24","v0.0.23","v0.0.22","v0.0.21","v0.0.20","v0.0.19","v0.0.18","v0.0.17","v0.0.16","v0.0.15","v0.0.14","v0.0.13","v0.0.12","v0.0.11","v0.0.10","v0.0.9","v0.0.8","v0.0.7","v0.0.6","v0.0.5","v0.0.4","v0.0.3","v0.0.2","v0.0.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-67546.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}