Roslyn CodeLens MCP Server — Rce (CVE-2026-45555)
Date: 2026-05
Attack vector: rce
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-45555
CWE: CWE-94
CVSS: 7.8 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)

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.


Mitigations:

Architectural layers (MAESTRO):