CVE-2022-36883: Jenkins Git Auth Bypass Vulnerability

CVE-2022-36883 Overview

CVE-2022-36883 is a Missing Authorization vulnerability affecting the Jenkins Git Plugin. A missing permission check in Jenkins Git Plugin version 4.11.3 and earlier allows unauthenticated attackers to trigger builds of jobs configured to use an attacker-specified Git repository and to cause them to check out an attacker-specified commit. This vulnerability enables remote attackers to manipulate CI/CD pipelines without any authentication, potentially leading to supply chain attacks.

Critical Impact

Unauthenticated attackers can trigger arbitrary builds with attacker-controlled Git repositories and commits, potentially injecting malicious code into software build pipelines.

Affected Products

• Jenkins Git Plugin 4.11.3 and earlier versions
• All Jenkins instances using vulnerable Git Plugin versions
• CI/CD pipelines configured with Git repository integrations

Discovery Timeline

• 2022-07-27 - CVE-2022-36883 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-36883

Vulnerability Analysis

This vulnerability is classified under CWE-862 (Missing Authorization). The Jenkins Git Plugin fails to implement proper permission checks on certain endpoints, allowing unauthenticated users to interact with the plugin's functionality. The flaw enables attackers to remotely trigger build jobs configured with Git repositories, specifying arbitrary repository URLs and commit hashes without requiring any credentials or session tokens.

The attack can be executed entirely over the network without user interaction. While the vulnerability does not directly expose confidential data, it has significant integrity implications as attackers can influence what code gets built and potentially deployed through the CI/CD pipeline.

Root Cause

The root cause is a missing permission check (CWE-862) in the Jenkins Git Plugin's request handling logic. The plugin exposes endpoints that should require authentication and authorization but fails to enforce these security controls. This allows any network-accessible user to invoke build triggers that should be restricted to authenticated Jenkins users with appropriate permissions.

Attack Vector

The vulnerability is exploitable via network-based attacks targeting Jenkins instances with the vulnerable Git Plugin installed. An attacker can craft HTTP requests to the Jenkins server that trigger build jobs, specifying:

1. An attacker-controlled Git repository URL
2. A specific commit hash to check out

The attack does not require any privileges (PR:N), user interaction (UI:N), and can be performed with low complexity (AC:L). This enables supply chain attack scenarios where malicious code could be introduced into build processes.

The exploitation mechanism involves sending specially crafted requests to Jenkins endpoints exposed by the Git Plugin. These requests bypass the intended authorization controls, allowing unauthenticated users to trigger builds with arbitrary Git repository configurations. For detailed technical information, see the Jenkins Security Advisory SECURITY-284.

Detection Methods for CVE-2022-36883

Indicators of Compromise

• Unexpected build job executions from unrecognized Git repository URLs
• Build logs showing checkout operations from repositories not configured by administrators
• HTTP requests to Git Plugin endpoints from unauthenticated sources
• Unusual commit hashes being checked out that don't match expected development branches

Detection Strategies

• Monitor Jenkins access logs for unauthenticated requests to Git Plugin endpoints
• Audit build job execution history for unauthorized triggers or unexpected Git repository URLs
• Implement alerting on build jobs triggered without associated authenticated user sessions
• Review Jenkins security logs for permission bypass attempts

Monitoring Recommendations

• Enable comprehensive audit logging for all Jenkins build triggers and Git operations
• Configure SIEM rules to detect patterns of unauthenticated Git Plugin endpoint access
• Monitor for anomalous build activity patterns, especially outside normal development hours
• Track all Git repository URL changes in build configurations for unauthorized modifications

How to Mitigate CVE-2022-36883

Immediate Actions Required

• Update Jenkins Git Plugin to version 4.11.4 or later immediately
• Restrict network access to Jenkins instances using firewall rules
• Review recent build history for any suspicious or unauthorized build triggers
• Audit Git repository configurations for any unauthorized changes

Patch Information

Jenkins has released a security update to address this vulnerability. Organizations should upgrade the Git Plugin to version 4.11.4 or later, which includes proper permission checks on the affected endpoints. For complete patch details, refer to the Jenkins Security Advisory SECURITY-284. Additional discussion is available on the OpenWall OSS-Security mailing list.

Workarounds

• Place Jenkins behind a reverse proxy with authentication requirements
• Implement network-level access controls to restrict Jenkins access to trusted IP ranges only
• Disable anonymous access to Jenkins entirely if not required for operations
• Consider temporarily disabling the Git Plugin if patching is not immediately possible

# Configuration example for restricting Jenkins access via iptables
# Allow access only from trusted internal network
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP