Arbitrary Code Execution in Z.ai ZCode

Executive Summary

CVE-2026-88755 is a vulnerability in Z.ai ZCode v3.11.2.6792 where the client automatically connects to MCP servers defined in a repository's workspace configuration without user approval. This allows attackers to execute arbitrary code by opening a crafted repository, bypassing security controls and enabling zero-interaction remote code execution.

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Detection Guidance

Check ZCode client logs for unexpected MCP server connections or spawned processes like calc.exe. Monitor network traffic for outbound connections to unknown servers when opening repositories. Inspect .zcode/config.json files in repositories for suspicious MCP server entries.

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Impact Analysis

This vulnerability can allow attackers to execute arbitrary code on your system without your knowledge by simply opening a malicious repository. It can also lead to information disclosure, such as exfiltration of sensitive credentials like API keys or passwords, as the client connects to attacker-controlled servers automatically.

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Compliance Impact

This vulnerability could lead to non-compliance with GDPR and HIPAA due to unauthorized code execution and information disclosure. Attackers may exfiltrate sensitive credentials like API keys, JWT tokens, and SSH passwords by exploiting the flaw, which violates data protection requirements under these regulations.

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Mitigation Strategies

Disable automatic MCP server connections in ZCode settings if available. Avoid opening untrusted repositories in ZCode. Use network monitoring tools to block unauthorized outbound connections. Update ZCode to the latest version if a patch is released.

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