CSRF protection for any URL can be bypassed in Jenkins Pipeline: Input Step Plugin

Pipeline: Input Step Plugin 451.vf1a_a_4f405289 and earlier does not restrict or sanitize the optionally specified ID of the input step. This ID is used for the URLs that process user interactions for the given input step (proceed or abort) and is not correctly encoded.

This allows attackers able to configure Pipelines to have Jenkins build URLs from input step IDs that would bypass the CSRF protection of any target URL in Jenkins when the input step is interacted with.

Pipeline: Input Step Plugin 456.vd8a_957db_5b_e9 limits the characters that can be used for the ID of input steps in Pipelines to alphanumeric characters and URL-safe punctuation. Pipelines with input steps having IDs with prohibited characters will fail with an error.

This includes Pipelines that have already been started but not finished before Jenkins is restarted to apply this update.

Pipeline: Declarative Plugin provides an input directive that is internally using the input step, and specifies a non-default ID if not user-defined. Pipeline: Declarative Plugin 2.2114.v2654ca_721309 and earlier may specify values incompatible with this new restriction on legal values: input directives in a stage use the stage name (which may include prohibited characters) and input directives in a matrix will use a value generated from the matrix axis values (which always includes prohibited characters). Administrators are advised to update Pipeline: Input Step Plugin and Pipeline: Declarative Plugin at the same time, ideally while no Pipelines are running.