What’s Vulnerable › Vulnerabilities

CVE-2026-45555: Roslyn CodeLens MCP Server: Untrusted Roslyn Analyzer Execution via get_diagnostics Leads to Arbitrary Code Execution

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-29 · updated 2026-07-21
• Weakness: CWE-94

Description

Roslyn CodeLens MCP Server is a Roslyn-based MCP server providing semantic code intelligence for .NET codebases. From 0.0.9 to 1.17.0, the get_diagnostics MCP tool loads and executes all DiagnosticAnalyzer assemblies referenced by the target solution without any allowlist, signature check, or user confirmation; includeAnalyzers defaults to true, so no explicit opt-in is required. An attacker who can place a malicious .csproj referencing an attacker-controlled DLL in a location the victim opens with the MCP server will achieve arbitrary code execution in the server process with the server's OS privileges. This vulnerability is fixed in 1.17.0.

Affected products

• MarcelRoozekrans roslyn-codelens-mcp: from 0.0.9, < 1.17.0

References

• https://github.com/MarcelRoozekrans/roslyn-codelens-mcp/security/advisories/GHSA-552p-8f74-6x7q
• https://github.com/MarcelRoozekrans/roslyn-codelens-mcp/security/advisories/GHSA-552p-8f74-6x7q

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