Arbitrary file read vulnerability in workspace browsers
SECURITY-2197 / CVE-2021-21615
Due to a time-of-check to time-of-use (TOCTOU) race condition, the file browser for workspaces, archived artifacts, and $JENKINS_HOME/userContent/
follows symbolic links to locations outside the directory being browsed in Jenkins 2.275 and LTS 2.263.2.
This allows attackers with Job/Workspace permission and the ability to control workspace contents, e.g., with Job/Configure permission or the ability to change SCM contents, to create symbolic links that allow them to access files outside workspaces using the workspace browser.
NOTE: This issue is caused by an incorrectly applied fix for SECURITY-1452 / CVE-2021-21602 in the 2021-01-13 security advisory.