CVE-2023-41937
📋 TL;DR
This vulnerability in Jenkins Bitbucket Plugin allows attackers to steal Bitbucket credentials stored in Jenkins by sending malicious webhook payloads. The plugin blindly trusts URLs from webhook data and uses stored credentials to connect to attacker-controlled servers. Organizations using affected plugin versions with Bitbucket credentials configured are at risk.
💻 Affected Systems
- Jenkins Bitbucket Push and Pull Request Plugin
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain access to Bitbucket repositories, potentially leading to source code theft, injection of malicious code, or lateral movement to connected systems.
Likely Case
Bitbucket credentials are exfiltrated, allowing unauthorized access to source code repositories and potential CI/CD pipeline compromise.
If Mitigated
With proper network segmentation and credential isolation, impact is limited to the Jenkins instance itself.
🎯 Exploit Status
Exploitation requires sending crafted webhook payloads to Jenkins, which may be accessible if Jenkins is exposed or if attackers can trigger webhooks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.8.4
Vendor Advisory: https://www.jenkins.io/security/advisory/2023-09-06/#SECURITY-3165
Restart Required: Yes
Instructions:
1. Update Jenkins Bitbucket Push and Pull Request Plugin to version 2.8.4 or later via Jenkins Plugin Manager. 2. Restart Jenkins to apply the update.
🔧 Temporary Workarounds
Disable webhook processing
allTemporarily disable Bitbucket webhook processing in Jenkins until patching is complete.
Navigate to Jenkins > Manage Jenkins > Configure System > Bitbucket Endpoints and disable webhook processing
Restrict webhook sources
linuxConfigure firewall rules to only allow webhook traffic from trusted Bitbucket IP ranges.
iptables -A INPUT -p tcp --dport 8080 -s <bitbucket_ip_range> -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP
🧯 If You Can't Patch
- Isolate Jenkins instance from internet and restrict network access to only required Bitbucket endpoints
- Use separate, limited-scope credentials for Bitbucket integration and rotate them regularly
🔍 How to Verify
Check if Vulnerable:
Check Jenkins plugin version: Navigate to Manage Jenkins > Manage Plugins > Installed tab, search for 'Bitbucket Push and Pull Request Plugin' and verify version is between 2.4.0 and 2.8.3.Check Version:
curl -s http://jenkins-host/pluginManager/api/json?depth=1 | jq '.plugins[] | select(.shortName=="bitbucket-push-and-pull") | .version'Verify Fix Applied:
Verify plugin version is 2.8.4 or higher in Jenkins Plugin Manager.📡 Detection & Monitoring
Log Indicators:
- Unusual outbound connections from Jenkins to unfamiliar IPs/domains
- Failed authentication attempts to Bitbucket from Jenkins
Network Indicators:
- Jenkins making HTTP requests to suspicious external domains following webhook receipt
SIEM Query:
source="jenkins.log" AND "Bitbucket" AND ("webhook" OR "payload") AND ("error" OR "failed" OR "unauthorized")