CVE-2024-39458

What it actually does

Jenkins Structs Plugin 337.v1b_04ea_4df7c8 and earlier may write sensitive build-step parameter values to the default Jenkins system log when a build step fails to configure. The flaw is an information disclosure issue: secrets such as passwords, tokens, API keys, or other credential-like values supplied as step parameters can be exposed in diagnostic warning messages. It does not directly provide code execution or privilege escalation, but any user, administrator, log collector, or attacker with access to Jenkins system logs may be able to recover exposed secrets.

Why it matters to the business

The main risk is credential leakage from Jenkins logs. Exposed credentials can allow unauthorized access to source code repositories, artifact registries, cloud services, deployment systems, or internal applications that Jenkins integrates with. Because Jenkins commonly holds highly privileged automation secrets, even a low-severity logging flaw can create broader operational risk if logs are widely retained, forwarded to SIEM platforms, or accessible to support and operations teams. This CVE is not listed in CISA KEV, has low EPSS, and has no known mature public exploitation reported in the provided data, so remediation should be prioritized as part of normal Jenkins plugin patching and credential hygiene rather than emergency incident response unless sensitive values are found in logs.

How an attack unfolds

An attacker first needs a way to cause Jenkins to process a malformed or invalid build-step configuration that includes sensitive values as step parameters, or they may benefit from an administrator or pipeline author accidentally doing so. In affected versions of the Structs Plugin, the failed configuration path logs a warning containing diagnostic details. Those diagnostics can include the parameter values supplied to the failed step, including secrets. The attacker then obtains access to the default Jenkins system log directly through Jenkins administrative/logging interfaces, through filesystem access to Jenkins log files, or indirectly through centralized log collection. If secrets are present, the attacker can reuse them against connected systems such as Git providers, CI/CD deployment targets, cloud APIs, container registries, or artifact repositories.

How to fix it

Upgrade the Jenkins Structs Plugin to a version newer than 337.v1b_04ea_4df7c8, preferably the latest version compatible with the deployed Jenkins LTS/core version. After upgrading, restart Jenkins if required and confirm the updated plugin is active. If immediate upgrade is not possible, reduce exposure by restricting who can configure jobs and Pipelines, limiting access to Jenkins system logs, limiting access to centralized log indexes containing Jenkins logs, and avoiding direct use of plaintext secrets as build-step parameters. Treat Jenkins logs generated while the vulnerable plugin was installed as potentially sensitive. Review and rotate any credentials found in those logs, including repository tokens, cloud keys, deployment credentials, webhook secrets, and artifact registry credentials.

How to confirm the fix worked

Confirm the installed Structs Plugin version is newer than 337.v1b_04ea_4df7c8 from Jenkins plugin management, the Jenkins CLI, or the plugin inventory on disk. Verify Jenkins has loaded the upgraded plugin after any restart. Review Jenkins system logs generated before the upgrade for warning messages from Structs Plugin or related describable/build-step configuration code that contain credential-like fields. Validate that log access is restricted to authorized administrators and that centralized log platforms apply masking, retention limits, and access controls for Jenkins logs. Where feasible, test in a non-production Jenkins instance by causing a build-step configuration failure with a harmless sentinel value and confirming the sentinel is not written to system logs after the upgrade.

Typical attack path

1. Identify a Jenkins controller running Structs Plugin 337.v1b_04ea_4df7c8 or earlier.
2. Obtain permission to configure jobs, submit Pipeline/build-step definitions, influence shared library code, or otherwise cause build-step configuration attempts.
3. Submit or trigger an invalid build-step configuration that includes credential-like parameter values.
4. Cause the Structs Plugin configuration failure path to emit a warning to the default Jenkins system log.
5. Access Jenkins system logs through the Jenkins UI, controller filesystem, support bundles, backups, or centralized log aggregation.
6. Search the logs for leaked passwords, tokens, API keys, or other secrets.
7. Use any recovered secrets to access connected repositories, deployment environments, cloud accounts, registries, or internal services.

How to detect it

To determine whether this was already exploited or accidentally triggered, review Jenkins controller system logs, archived logs, support bundles, container logs, and centralized logging/SIEM indexes covering the period when Structs Plugin 337.v1b_04ea_4df7c8 or earlier was installed. Focus on WARNING-level messages around failed build-step, Pipeline, or job configuration events, especially messages referencing Jenkins Structs Plugin classes such as org.jenkinsci.plugins.structs or describable model/configuration handling. Search for credential-like parameter names and high-entropy values appearing near configuration failure messages. Useful sources include $JENKINS_HOME/logs/jenkins.log, /var/log/jenkins/jenkins.log, systemd journal entries for the Jenkins service, Kubernetes pod logs for Jenkins controllers, Docker logs for Jenkins containers, Jenkins support-core bundles, and SIEM indexes receiving Jenkins application logs. If secrets are found, determine their exposure window, identify all systems receiving the logs, rotate the affected credentials, and investigate downstream use of those credentials in authentication logs for repositories, cloud platforms, registries, and deployment systems.

• Structs Plugin 337.v1b_04ea_4df7c8
• $JENKINS_HOME/logs/jenkins.log
• /var/log/jenkins/jenkins.log
• org.jenkinsci.plugins.structs
• org.jenkinsci.plugins.structs.describable
• WARNING
• password=
• passwd=
• pwd=
• token=
• secret=
• apiKey=
• apikey=
• accessKey=
• access_key=
• secretKey=
• secret_key=
• privateKey=
• private_key=
• authorization=
• Bearer
• BEGIN PRIVATE KEY
• BEGIN RSA PRIVATE KEY

What your security team should do

• Upgrade Jenkins Structs Plugin to the latest available compatible release, ensuring it is newer than 337.v1b_04ea_4df7c8.
• Inventory Jenkins controllers and plugin versions to identify any remaining affected instances.
• Restrict Jenkins job configuration, Pipeline authoring, and script/shared-library modification privileges to trusted users.
• Restrict access to Jenkins system logs, support bundles, backups, and centralized log indexes that ingest Jenkins logs.
• Search historical Jenkins logs for exposed credential-like values and rotate any confirmed leaked secrets.
• Add SIEM detections for Jenkins warning logs containing credential-like parameter names such as password, token, secret, apiKey, accessKey, privateKey, or authorization.
• Review Jenkins credential handling practices and prefer Jenkins Credentials Binding or approved secret-management integrations over plaintext parameters.
• Reduce Jenkins log retention where business requirements permit and ensure sensitive logs are encrypted and access-controlled.