CVE-2026-42520: Jenkins Credentials Binding RCE Flaw

CVE-2026-42520 Overview

Jenkins Credentials Binding Plugin version 719.v80e905ef14eb_ and earlier contains a path traversal vulnerability due to improper sanitization of file names for file and zip file credentials. This security flaw allows attackers who can provide credentials to a job to write files to arbitrary locations on the node filesystem. When Jenkins is configured to allow a low-privileged user to configure file or zip file credentials used for a job running on the built-in node, this vulnerability can lead to remote code execution.

Critical Impact

Attackers with low-privilege access to configure credentials can achieve arbitrary file write, potentially leading to remote code execution on Jenkins nodes.

Affected Products

• Jenkins Credentials Binding Plugin version 719.v80e905ef14eb_ and earlier
• Jenkins installations allowing low-privileged users to configure file or zip file credentials
• Jenkins environments with jobs running on the built-in node

Discovery Timeline

• 2026-04-29 - CVE CVE-2026-42520 published to NVD
• 2026-04-29 - Last updated in NVD database

Technical Details for CVE-2026-42520

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Path Traversal), a category of input validation flaws where an application fails to properly neutralize special path elements. The Jenkins Credentials Binding Plugin does not adequately sanitize file names when handling file and zip file credentials, allowing malicious path sequences to escape intended directory boundaries.

The vulnerability requires network access and user authentication with low privileges, though exploitation complexity is high due to specific configuration requirements. Successful exploitation impacts confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause lies in insufficient input validation within the file name handling logic of the Credentials Binding Plugin. When file or zip file credentials are processed, the plugin fails to strip or reject directory traversal sequences (such as ../) from file names. This allows an attacker to craft credential file names that, when written, escape the intended credential storage directory and write to arbitrary filesystem locations.

Attack Vector

The attack exploits the network-accessible Jenkins interface and requires the following conditions:

1. The attacker must have low-privilege access to Jenkins with permissions to configure credentials
2. The attacker must be able to provide file or zip file credentials to a job
3. A job using these credentials must run on the built-in node
4. Jenkins must be configured to allow low-privileged users to configure file or zip file credentials

By providing a maliciously crafted credential with a file name containing path traversal sequences, an attacker can write files to arbitrary locations on the Jenkins node filesystem. This arbitrary file write capability can be leveraged for remote code execution by overwriting configuration files, placing malicious scripts in execution paths, or manipulating other sensitive system files.

Detection Methods for CVE-2026-42520

Indicators of Compromise

• Unexpected file modifications in directories outside the Jenkins credentials storage path
• Credential file names containing path traversal sequences such as ../ or absolute paths
• Unusual file creation activity on the built-in Jenkins node
• Jenkins audit logs showing credential configuration by low-privileged users followed by suspicious job executions

Detection Strategies

• Monitor Jenkins audit logs for credential configuration activities by users with minimal privileges
• Implement file integrity monitoring (FIM) on critical system directories on Jenkins nodes
• Review credential file names for suspicious path traversal patterns during security audits
• Enable enhanced logging for the Credentials Binding Plugin to track credential usage

Monitoring Recommendations

• Deploy SentinelOne agents on Jenkins nodes to detect and alert on anomalous file system activity
• Configure alerting for any file write operations outside expected Jenkins directories
• Establish baseline behavioral patterns for Jenkins job execution and monitor for deviations
• Regularly audit user permissions to ensure least-privilege principles are enforced

How to Mitigate CVE-2026-42520

Immediate Actions Required

• Update the Jenkins Credentials Binding Plugin to the latest patched version immediately
• Review and restrict permissions for configuring file and zip file credentials to trusted administrators only
• Audit existing credentials for any suspicious file names containing path traversal sequences
• Consider moving job execution from the built-in node to dedicated agent nodes

Patch Information

Jenkins has released a security advisory addressing this vulnerability. Refer to the Jenkins Security Advisory #SECURITY-3672 for official patch information and updated plugin versions. Organizations should apply the security update as soon as possible to remediate this vulnerability.

Workarounds

• Restrict credential configuration permissions to trusted administrators only until the patch can be applied
• Avoid running jobs that use file or zip file credentials on the built-in node
• Implement additional access controls to limit who can configure and manage credentials
• Use agent nodes instead of the built-in node for jobs requiring file credentials

# Review Jenkins plugin version
# Navigate to Manage Jenkins > Manage Plugins > Installed
# Verify Credentials Binding Plugin version and update if below patched version

# Restrict credential permissions via Jenkins configuration
# Manage Jenkins > Configure Global Security > Authorization
# Ensure only trusted administrators have Credentials/Create and Credentials/Update permissions