Published : Aug. 6, 2026, 12:16 a.m. | 1 hour, 33 minutes ago
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.
Severity: 9.3 | CRITICAL
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🤖 AI-Generated Patch Solution
Google Gemini (gemini-2.5-flash) • CVE: CVE-2026-67531
N/A
Upon detection or suspicion of compromise related to CVE-2026-67531, immediate actions are critical to contain the threat and prevent further damage.
a. Isolate Affected Systems: If the vulnerability is confirmed or highly suspected, immediately disconnect or logically isolate all affected servers and services from the network. This includes web servers, application servers, message queue consumers, and any other systems utilizing the vulnerable component. This can be achieved through firewall rules, network segmentation, or physical disconnection.
b. Block Known Exploit Indicators: If specific exploit patterns, IP addresses, or payload signatures are identified, implement immediate blocking rules on perimeter firewalls, Web Application Firewalls (WAFs), and Intrusion Prevention Systems (IPS).
c. Review Logs for Compromise: Conduct an urgent forensic review of application logs, system logs, web server logs, and security event logs for signs of exploitation. Look for unusual process creation, outbound network connections from application servers, unexpected file modifications, elevated privileges, or any error messages indicative of deserialization failures or unusual input. Focus on logs from the period immediately preceding and following the suspected compromise.
d. Disable Vulnerable Functionality: If immediate patching or isolation is not feasible, consider temporarily disabling or restricting access to the specific features or services that utilize the vulnerable component. For example, if the vulnerability is in a message queue client, temporarily halt message processing by affected consumers or restrict the types of messages they can process.
e. Backup Critical Data: Perform immediate backups of critical data and system configurations from potentially compromised systems. Ensure these backups are stored securely and are not themselves compromised.
f. Notify Stakeholders: Inform relevant internal teams (e.g., incident response, development, IT operations, legal) and external parties (e.g., customers, regulatory bodies) as per your organization's incident response plan.
2. PATCH AND UPDATE INFORMATION
The primary and most effective remediation for CVE-2026-67531 is to apply the vendor-provided security patch.
a. Identify Vulnerable Components: Determine all instances of the affected software, library, or framework component across your environment. This requires a comprehensive asset inventory and software bill of materials (SBOM) analysis.
b. Obtain Official Patches: Monitor the official vendor security advisories and release channels for the specific patch addressing CVE-2026-67531. Ensure the patch is downloaded directly from the trusted vendor source to prevent supply chain attacks.
c. Prioritize Patch Deployment: Prioritize patching critical production systems, internet-facing applications, and systems handling sensitive data. Develop a staggered deployment plan, starting with non-production environments for testing.
d. Test Patches Thoroughly: Before deploying to production, thoroughly test the patch in a staging or development environment to ensure compatibility and prevent service disruption. Verify that the patch resolves the vulnerability without introducing new issues.
e. Rollback Plan: Prepare a rollback plan in case the patch causes unexpected issues in production.
f. Verify Patch Application: After deployment, verify that the patch has been successfully applied