Jenkins 2.275 and LTS 2.263.2 allows reading arbitrary files using the file browser for workspaces and archived artifacts due to a time-of-check to time-of-use (TOCTOU) race condition.
https://www.jenkins.io/security/advisory/2021-01-26/#SECURITY-2197
http://www.openwall.com/lists/oss-security/2021/01/26/2