CVE-2023-27898
📋 TL;DR
This stored cross-site scripting (XSS) vulnerability in Jenkins allows attackers to inject malicious scripts into error messages about plugin incompatibility. Attackers who can provide plugins to Jenkins update sites can exploit this to execute arbitrary JavaScript in users' browsers. Jenkins instances versions 2.270-2.393 and LTS 2.277.1-2.375.3 are affected.
💻 Affected Systems
- Jenkins
📦 What is this software?
Jenkins by Jenkins
Jenkins by Jenkins
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator credentials, perform actions as authenticated users, or compromise the Jenkins server through subsequent attacks.
Likely Case
Attackers could hijack user sessions, steal sensitive data, or perform unauthorized actions within Jenkins.
If Mitigated
With proper plugin source controls and network segmentation, impact is limited to users viewing malicious error messages.
🎯 Exploit Status
Exploitation requires ability to provide malicious plugins to update sites; attackers need to trigger the specific error message display.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Jenkins 2.394, LTS 2.375.4
Vendor Advisory: https://www.jenkins.io/security/advisory/2023-03-08/#SECURITY-3037
Restart Required: Yes
Instructions:
1. Backup Jenkins configuration and data. 2. Upgrade to Jenkins 2.394 or LTS 2.375.4 or later. 3. Restart Jenkins service. 4. Verify upgrade completed successfully.
🔧 Temporary Workarounds
Restrict Plugin Sources
allOnly use trusted, official Jenkins update sites and disable untrusted plugin sources.
Configure Jenkins to only use https://updates.jenkins.io/update-center.json
Content Security Policy
allImplement strict Content Security Policy headers to mitigate XSS impact.
🧯 If You Can't Patch
- Implement network segmentation to isolate Jenkins from untrusted networks
- Monitor and audit all plugin installations and update site configurations
🔍 How to Verify
Check if Vulnerable:
Check Jenkins version via Manage Jenkins > About Jenkins or via CLICheck Version:
java -jar jenkins.war --versionVerify Fix Applied:
Verify version is 2.394+ or LTS 2.375.4+ and test that plugin incompatibility messages are properly escaped📡 Detection & Monitoring
Log Indicators:
- Unusual plugin installation attempts
- Multiple plugin compatibility errors
- Requests to unusual update sites
Network Indicators:
- Outbound connections to non-standard update sites
- Unexpected plugin downloads
SIEM Query:
source="jenkins.log" AND ("plugin incompatibility" OR "update site")