CVE-2026-42519

The Script Security plugin in Jenkins before version 1.18.1 may allow remote attackers to bypass a Groovy sandbox protection mechanism via a plugin that performs direct field access or get/set array operations.

Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier does not check calls from sandboxed scripts to methods added dynamically to a class at runtime, allowing attackers with permission to define and run sandboxed scripts, including Pipelines, to bypass the sandbox protection and execute code outside the sandbox.

Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier downloads a JAR file specified by URL twice, confirming the approval of the first download and loading the classpath entries from the second, allowing attackers able to define classpath entries to execute arbitrary code in the context of the Jenkins controller JVM.

Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier automatically approves the classpath entries in an item configuration when a user with Overall/Administer permission copies the item, or updates that configuration through the REST API or CLI, allowing attackers able to define classpath entries to execute arbitrary code in the context of the Jenkins controller JVM.

Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier does not reject @Builder annotations whose builderStrategy member names an arbitrary class, allowing attackers with permission to define and run sandboxed scripts, including Pipelines, to execute code outside the sandbox if a suitable class is present on the classpath of the component that evaluates the script.

Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier does not reject the @GroovyASTTransformationClass annotation, allowing attackers with permission to define and run sandboxed scripts, including Pipelines, to run an arbitrary AST transformation at compile time, bypassing the sandbox protection and executing arbitrary code in the context of the Jenkins controller JVM.

Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier checks the operations Groovy will perform with the elements it reads from a collection that a sandboxed script casts to another type but performs the cast on the collection itself, allowing attackers with permission to define and run sandboxed scripts, including Pipelines, to bypass the sandbox protection and execute arbitrary code in the context of the Jenkins controller JVM.

Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier does not intercept operations performed on a null receiver (method calls, property and attribute accesses, and array accesses), allowing attackers with permission to define and run sandboxed scripts, including Pipelines, to bypass the sandbox protection and execute arbitrary code in the context of the Jenkins controller JVM.

Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier does not check the method called through the proxy created when a sandboxed script coerces a value to an interface, if the value inherits a method of the same name as an interface method, allowing attackers with permission to define and run sandboxed scripts, including Pipelines, to bypass the sandbox protection and execute arbitrary code in the context of the Jenkins controller JVM.