GHSA-8hmv-92wm-39ch

Various features in Jenkins redirect users to partially user-controlled URLs inside Jenkins. To prevent open redirect vulnerabilities, Jenkins limits redirections to safe URLs (neither absolute nor scheme-relative/network-path reference). In Jenkins 2.499 and earlier, LTS 2.492.1 and earlier, redirects starting with backslash (`\`) characters are considered safe. This allows attackers to perform phishing attacks by having users go to a Jenkins URL that will forward them to a different site, because browsers interpret these characters as part of scheme-relative redirects. Jenkins 2.500, LTS 2.492.2 considers redirects to URLs starting with backslash (`\`) characters to be unsafe, rejecting such redirects.