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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.

PUBLISHED Reserved 2026-05-12 | Published 2026-05-29 | Updated 2026-05-29 | Assigner GitHub_M




HIGH: 7.8CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Problem types

CWE-94: Improper Control of Generation of Code ('Code Injection')

Product status

>= 0.0.9, < 1.17.0
affected

References

github.com/...ns-mcp/security/advisories/GHSA-552p-8f74-6x7q exploit

github.com/...ns-mcp/security/advisories/GHSA-552p-8f74-6x7q

cve.org (CVE-2026-45555)

nvd.nist.gov (CVE-2026-45555)

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