Code InjectionWeakness · CWE-94

CVE-2026-45555

HIGH · 7.8 CVSS v3.1 Published 2026-05-29

Mitigation only

No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.

See remediation →

81/100

Remediation priority · High

No privileges

Official description

NVD · unedited

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.

Technical summary

dbcve analysis · high confidence

The get_diagnostics MCP tool in Roslyn CodeLens MCP Server versions 0.0.9 through 1.17.0 automatically loads and executes all DiagnosticAnalyzer assemblies referenced by a target solution without any allowlist, signature verification, or user confirmation. Since includeAnalyzers defaults to true, opening a malicious .csproj file that references an attacker-controlled DLL enables arbitrary code execution in the server process with the server's OS privileges.

MitigationUpgrade to version 1.17.0 or later which implements an allowlist or signature verification for DiagnosticAnalyzer assemblies. Avoid opening untrusted .csproj files or solutions with the MCP server until patched.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown

From the vector

Attack vector: Local
Complexity: Low
Privileges: None
User interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

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

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Identify the Roslyn CodeLens MCP Server installation

Locate the MCP server installation directory or package and retrieve its version information (check package.json, DLL metadata, or server logs)

Affected if Version is present and less than 1.17.0 (v1.17.0 or later contains the fix)
Verify the get_diagnostics tool is enabled

Check the MCP server configuration or documentation for whether the get_diagnostics tool is available and activated

Affected if The get_diagnostics tool is enabled and accessible in the server configuration
Confirm includeAnalyzers setting

Inspect the server configuration files or runtime settings for the includeAnalyzers parameter (note: it defaults to true in vulnerable versions)

Affected if includeAnalyzers is set to true or is not explicitly set to false (defaults to true in affected versions)
Review which solutions the server has opened

Check server logs, recent activity, or workspace history to see what .csproj or .sln files have been opened by the MCP server

Affected if Any .NET solution or project files were opened by the server; opening untrusted solutions poses the highest risk

A user is affected if they have the Roslyn CodeLens MCP Server installed with a version below 1.17.0 and have used the get_diagnostics tool to open any .NET solution or project, since includeAnalyzers defaults to true and allows unauthenticated DiagnosticAnalyzer assembly execution.

Generated from the published advisory. Verify against your own configuration.

Remediation

dbcve · scoped

Mitigation available No clean upgrade yet — mitigate in the meantime

Mitigation

Upgrade to version 1.17.0 or later which implements an allowlist or signature verification for DiagnosticAnalyzer assemblies. Avoid opening untrusted .csproj files or solutions with the MCP server until patched.

Recommended fix High confidence

1.17.0 or later

Upgrade the Roslyn CodeLens MCP Server to version 1.17.0 or later to obtain the fixed version that includes allowlist, signature check, and user confirmation for DiagnosticAnalyzer assemblies

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory

Consultation4.0 h
Implementation8.0 h
Testing6.0 h
Review / QA4.0 h

22.0 hours of engineering $3,860

Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

Scan for this in your stack

Free · runs locally

dbcve dependency scanner

Check whether your project pulls in CVE-2026-45555 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

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References

Primary sources

github.com
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-45555 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2026-45555?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsA vendor remedy is published

Severity 7.8 High

Exploit likelihood EPSS, next 30 days 0.1%

Remediation

A high-priority fix

Have this fixed 22 hrs · Moderate

Typical engagement from $3,860

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2026-45555 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

CVSS breakdown

Am I affected?

Remediation

References