{"id":"CVE-2026-67531","state":"PUBLISHED","title":"FrontMCP: CodeCall sandbox escape -> host RCE via live Zod schema exposure by getTool","description":"FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). Prior to 1.5.7, the sandboxed codecall:execute tool exposes live host Zod schema instances to the script via getTool(), and because Zod v4 defines _zod as a non-configurable, non-writable own property, the ECMAScript Proxy invariants force the security membrane to hand back the raw host object, letting a script reach _zod.constr.constructor (the host Function constructor) and execute arbitrary code in the server process. A single tools/call is sufficient to escape the sandbox and achieve remote code execution as the server user, exposing everything the process holds such as OAuth client secrets, JWT_SECRET, session keys, database credentials, and cloud instance metadata. Because the framework's DEFAULT_AUTH_OPTIONS is public mode, an unconfigured server serves this to unauthenticated callers, and on authenticated servers an indirect prompt injection in tool output or fetched content can trigger it without a human attackerThis issue is fixed in version 1.5.7.","publishedAt":"2026-08-05T22:54:36.219Z","updatedAt":"2026-08-06T18:44:39.455Z","severity":{"score":9.3,"label":"Critical","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["agentfront frontmcp"],"affected":[{"vendor":"agentfront","product":"frontmcp","versions":[{"version":"< 1.5.7","status":"affected"}]}],"references":["https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px","https://github.com/agentfront/frontmcp/commit/209cddd19a8d4db0777f725b527818da7df6f67f"],"weaknesses":["CWE-94"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/67xxx/CVE-2026-67531.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-67531","state":"PUBLISHED","datePublished":"2026-08-05T22:54:36.219Z","dateUpdated":"2026-08-06T18:44:39.455Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-29T18:47:17.073Z"},"containers":{"cna":{"title":"FrontMCP: CodeCall sandbox escape -> host RCE via live Zod schema exposure by getTool","descriptions":[{"lang":"en","value":"FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). Prior to 1.5.7, the sandboxed codecall:execute tool exposes live host Zod schema instances to the script via getTool(), and because Zod v4 defines _zod as a non-configurable, non-writable own property, the ECMAScript Proxy invariants force the security membrane to hand back the raw host object, letting a script reach _zod.constr.constructor (the host Function constructor) and execute arbitrary code in the server process. A single tools/call is sufficient to escape the sandbox and achieve remote code execution as the server user, exposing everything the process holds such as OAuth client secrets, JWT_SECRET, session keys, database credentials, and cloud instance metadata. Because the framework's DEFAULT_AUTH_OPTIONS is public mode, an unconfigured server serves this to unauthenticated callers, and on authenticated servers an indirect prompt injection in tool output or fetched content can trigger it without a human attackerThis issue is fixed in version 1.5.7."}],"affected":[{"vendor":"agentfront","product":"frontmcp","versions":[{"version":"< 1.5.7","status":"affected"}]}],"references":[{"url":"https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px","name":"https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/agentfront/frontmcp/commit/209cddd19a8d4db0777f725b527818da7df6f67f","name":"https://github.com/agentfront/frontmcp/commit/209cddd19a8d4db0777f725b527818da7df6f67f","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":9.3,"baseSeverity":"CRITICAL","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-94","lang":"en","description":"CWE-94: Improper Control of Generation of Code ('Code Injection')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-05T22:54:36.219Z"},"source":{"advisory":"GHSA-mp29-fxh8-92px","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-06T18:38:14.596272Z","id":"CVE-2026-67531","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-06T18:44:39.455Z"}}]}}}