CVE-2026-67531 (GCVE-0-2026-67531)
Vulnerability from cvelistv5 – Published: 2026-08-05 22:54 – Updated: 2026-08-05 22:54
VLAI
EPSS
VEX
Title
FrontMCP: CodeCall sandbox escape -> host RCE via live Zod schema exposure by getTool
Summary
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.
Severity
CWE
- CWE-94 - Improper Control of Generation of Code ('Code Injection')
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/agentfront/frontmcp/security/a… | x_refsource_CONFIRM |
| https://github.com/agentfront/frontmcp/commit/209… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| agentfront | frontmcp |
Affected:
< 1.5.7
|
{
"containers": {
"cna": {
"affected": [
{
"product": "frontmcp",
"vendor": "agentfront",
"versions": [
{
"status": "affected",
"version": "\u003c 1.5.7"
}
]
}
],
"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\u00a0tool exposes live host Zod\u00a0schema instances to the script via\u00a0getTool(), and because Zod v4 defines\u00a0_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\u00a0_zod.constr.constructor\u00a0(the host Function\u00a0constructor) 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\u0027s\u00a0DEFAULT_AUTH_OPTIONS\u00a0is 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."
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 9.3,
"baseSeverity": "CRITICAL",
"privilegesRequired": "NONE",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"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",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "HIGH",
"vulnIntegrityImpact": "HIGH"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-94",
"description": "CWE-94: Improper Control of Generation of Code (\u0027Code Injection\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T22:54:36.219Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px"
},
{
"name": "https://github.com/agentfront/frontmcp/commit/209cddd19a8d4db0777f725b527818da7df6f67f",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/agentfront/frontmcp/commit/209cddd19a8d4db0777f725b527818da7df6f67f"
}
],
"source": {
"advisory": "GHSA-mp29-fxh8-92px",
"discovery": "UNKNOWN"
},
"title": "FrontMCP: CodeCall sandbox escape -\u003e host RCE via live Zod schema exposure by getTool"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-67531",
"datePublished": "2026-08-05T22:54:36.219Z",
"dateReserved": "2026-07-29T18:47:17.073Z",
"dateUpdated": "2026-08-05T22:54:36.219Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-67531",
"date": "2026-08-06",
"epss": "0.00434",
"percentile": "0.35686"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-67531\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-06T00:16:53.733\",\"lastModified\":\"2026-08-06T00:16:53.733\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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\u00a0tool exposes live host Zod\u00a0schema instances to the script via\u00a0getTool(), and because Zod v4 defines\u00a0_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\u00a0_zod.constr.constructor\u00a0(the host Function\u00a0constructor) 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\u0027s\u00a0DEFAULT_AUTH_OPTIONS\u00a0is 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\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"agentfront\",\"product\":\"frontmcp\",\"versions\":[{\"version\":\"\u003c 1.5.7\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":9.3,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"HIGH\",\"vulnIntegrityImpact\":\"HIGH\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-94\"}]}],\"references\":[{\"url\":\"https://github.com/agentfront/frontmcp/commit/209cddd19a8d4db0777f725b527818da7df6f67f\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px\",\"source\":\"security-advisories@github.com\"}]}}",
"vulnrichment": {
"containers": "{\"cna\": {\"title\": \"FrontMCP: CodeCall sandbox escape -\u003e host RCE via live Zod schema exposure by getTool\", \"problemTypes\": [{\"descriptions\": [{\"cweId\": \"CWE-94\", \"lang\": \"en\", \"description\": \"CWE-94: Improper Control of Generation of Code (\u0027Code Injection\u0027)\", \"type\": \"CWE\"}]}], \"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\"}}], \"references\": [{\"name\": \"https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px\", \"tags\": [\"x_refsource_CONFIRM\"], \"url\": \"https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px\"}, {\"name\": \"https://github.com/agentfront/frontmcp/commit/209cddd19a8d4db0777f725b527818da7df6f67f\", \"tags\": [\"x_refsource_MISC\"], \"url\": \"https://github.com/agentfront/frontmcp/commit/209cddd19a8d4db0777f725b527818da7df6f67f\"}], \"affected\": [{\"vendor\": \"agentfront\", \"product\": \"frontmcp\", \"versions\": [{\"version\": \"\u003c 1.5.7\", \"status\": \"affected\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-08-05T22:54:36.219Z\"}, \"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\\u00a0tool exposes live host Zod\\u00a0schema instances to the script via\\u00a0getTool(), and because Zod v4 defines\\u00a0_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\\u00a0_zod.constr.constructor\\u00a0(the host Function\\u00a0constructor) 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\u0027s\\u00a0DEFAULT_AUTH_OPTIONS\\u00a0is 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.\"}], \"source\": {\"advisory\": \"GHSA-mp29-fxh8-92px\", \"discovery\": \"UNKNOWN\"}}, \"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-67531\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-08-06T18:38:14.596272Z\"}}}], \"references\": [{\"url\": \"https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-08-06T18:39:10.006Z\"}}]}",
"cveMetadata": "{\"cveId\": \"CVE-2026-67531\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"state\": \"PUBLISHED\", \"assignerShortName\": \"GitHub_M\", \"dateReserved\": \"2026-07-29T18:47:17.073Z\", \"datePublished\": \"2026-08-05T22:54:36.219Z\", \"dateUpdated\": \"2026-08-06T18:44:39.455Z\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
Loading…
Loading…