CVE-2025-64132
📋 TL;DR
The Jenkins MCP Server Plugin vulnerability allows attackers to bypass permission checks and trigger unauthorized builds or access sensitive job/cloud configuration data. This affects Jenkins instances using MCP Server Plugin version 0.84.v50ca_24ef83f2 or earlier. Attackers with network access to Jenkins can exploit this to escalate privileges.
💻 Affected Systems
- Jenkins MCP Server Plugin
📦 What is this software?
Mcp Server by Jenkins
⚠️ Risk & Real-World Impact
Worst Case
Attackers could trigger arbitrary builds, modify job configurations, exfiltrate sensitive credentials from cloud configurations, and potentially achieve remote code execution through build processes.
Likely Case
Unauthorized users triggering builds they shouldn't have access to, leading to resource exhaustion, and accessing sensitive job configuration details.
If Mitigated
With proper network segmentation and authentication controls, impact would be limited to authorized users only.
🎯 Exploit Status
Exploitation requires some Jenkins knowledge but tools are documented. Attackers need network access and some level of Jenkins user access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.85 or later
Vendor Advisory: https://www.jenkins.io/security/advisory/2025-10-29/#SECURITY-3622
Restart Required: No
Instructions:
1. Access Jenkins web interface as administrator. 2. Navigate to Manage Jenkins > Manage Plugins. 3. Go to Available tab. 4. Search for 'MCP Server Plugin'. 5. Check the box and click Install without restart. 6. Verify plugin version is 0.85 or higher.
🔧 Temporary Workarounds
Disable MCP Server Plugin
allTemporarily disable the vulnerable plugin until patching is possible
Navigate to Manage Jenkins > Manage Plugins > Installed tab
Find MCP Server Plugin and click Disable
Restrict Network Access
allLimit Jenkins access to trusted networks only
Configure firewall rules to restrict Jenkins port (default 8080) to authorized IPs only
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Jenkins from untrusted networks
- Review and restrict user permissions to minimum required access levels
🔍 How to Verify
Check if Vulnerable:
Check Jenkins plugin manager for MCP Server Plugin version. If version is 0.84.v50ca_24ef83f2 or earlier, system is vulnerable.Check Version:
Navigate to Manage Jenkins > Manage Plugins > Installed tab and check MCP Server Plugin versionVerify Fix Applied:
Verify MCP Server Plugin version is 0.85 or higher in plugin manager.📡 Detection & Monitoring
Log Indicators:
- Unauthorized build triggers from unexpected users
- Access to job configuration endpoints by unauthorized users
- Failed permission checks in MCP tools
Network Indicators:
- Unusual MCP protocol traffic patterns
- Multiple build trigger requests from single user
SIEM Query:
source="jenkins.log" AND ("MCP" AND ("permission denied" OR "unauthorized access"))