CVE-2026-57280: Jenkins Script Security Plugin Sandbox Bypass (CVSS 8.8)

Technical summary

The Script Security Plugin applies sandboxing to user-supplied Groovy scripts to restrict dangerous operations. However, when typed for-each loops apply implicit type casts to their elements, the plugin fails to intercept these casts. This allows an attacker to invoke arbitrary constructors that bypass the normal sandbox checks. The vulnerability is rooted in incomplete AST transformation logic—the plugin does not properly instrument implicit casts in for-each loop contexts, creating a gap in the security perimeter. The issue affects all versions up to and including 1402.v94c9ce464861.

Business impact

This vulnerability poses a significant risk to Jenkins installations that use the Script Security Plugin and permit scripted pipelines or script console access to untrusted users or service accounts. A successful exploit enables remote code execution with the privileges of the Jenkins process, potentially leading to lateral movement, credential theft, or infrastructure compromise. Organizations relying on Jenkins for CI/CD with multi-tenant or shared-user environments face elevated exposure.

Affected systems

The vulnerability affects Jenkins Script Security Plugin version 1402.v94c9ce464861 and all earlier versions. Any Jenkins instance using this plugin is potentially vulnerable if it executes Groovy scripts from untrusted sources or grants script-execution privileges to low-privileged users. Systems that restrict script access only to highly trusted administrators may have reduced exposure.

Exploitability

Exploitation requires the attacker to have permission to submit or execute Groovy scripts in Jenkins (e.g., through pipeline jobs, declarative pipelines, or the Script Console). No interaction or special network conditions are required. The attack is reliable and deterministic once the attacker can inject a malicious script containing a typed for-each loop with an implicit type cast to trigger an arbitrary constructor invocation. The CVSS score of 8.8 (HIGH) reflects the low attack complexity and high impact when access conditions are met.

Remediation

Upgrade the Jenkins Script Security Plugin to a patched version released after 1402.v94c9ce464861. Verify the specific patch version against the official Jenkins advisories and your Jenkins management interface. Additionally, enforce strict access controls on script-execution features: limit Script Console access to trusted administrators, audit and approve pipeline definitions before execution, and consider using Jenkins configuration-as-code to audit all scripted pipeline changes.

Patch guidance

Check the Jenkins Security Advisory for Script Security Plugin for the patched release version. Apply the update through Jenkins's plugin manager or by manual WAR deployment, depending on your installation method. After patching, restart Jenkins and verify that the plugin version is correct in Manage Jenkins > Plugins. For large deployments, test the patch in a non-production environment first to ensure compatibility with existing pipelines.

Detection guidance

Monitor Jenkins execution logs for unusual Groovy script submissions, particularly those containing for-each loops with explicit type declarations followed by constructor invocations. Review Script Console history and pipeline job definitions for suspicious patterns. Implement Jenkins audit logging if not already enabled. Consider deploying Jenkins security scanning tools or SAST solutions that can detect sandbox-bypass patterns in Groovy code before execution.

Why prioritize this

This vulnerability merits prompt patching due to its high CVSS score (8.8), the trivial access requirements (authenticated user with script-execution permission), and the severity of the impact (arbitrary code execution). In multi-tenant Jenkins environments or instances accessible to developers outside your organization, this should be treated as a critical priority. Even in restricted environments, the ease of exploitation and the power of the resulting code execution justify expedited remediation.

Risk score, explained

The CVSS 3.1 score of 8.8 reflects: (1) Network-accessible attack vector, (2) Low attack complexity—no special conditions or tools required, (3) Low privilege requirement—attacker needs script-execution permission but not Jenkins admin rights, (4) High impact across confidentiality, integrity, and availability—arbitrary code execution permits data theft, system modification, and denial of service. The absence of user interaction and lack of scope change prevent a critical (9.0+) rating, but the overall risk remains severe.

Frequently asked questions