[org.jenkins-ci.main:jenkins-core] Path traversal vulnerability on Windows in Jenkins

The file browser for workspaces, archived artifacts, and userContent/ in Jenkins 2.314 and earlier, LTS 2.303.1 and earlier may interpret some paths to files as absolute on Windows.

This results in a path traversal vulnerability allowing attackers with Overall/Read permission (Windows controller) or Job/Workspace permission (Windows agents) to obtain the contents of arbitrary files.\n\nThe file browser in Jenkins 2.315, LTS 2.303.2 refuses to serve files that would be considered absolute paths.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-21683
• https://www.jenkins.io/security/advisory/2021-10-06/#SECURITY-2481
• http://www.openwall.com/lists/oss-security/2021/10/06/1
• https://github.com/advisories/GHSA-4pw5-r58h-fv24