CVE-2026-21589: Critical unauthenticated arbitrary file access in Atlassian products

Overview On October 5, 2026, Atlassian published a security advisory for CVE-2026-21589 , a critical arbitrary file access vulnerability affecting eight products: Bitbucket Data Center, Confluence Data Center, Jira Service Management Data Center, Jira Software Data Center, Bamboo Data Center, Crowd Data Center, Crucible, and Fisheye. Atlassian assigned the vulnerability a CVSSv4 score of 9.3 . An unauthenticated remote attacker who knows a target file’s exact name and path can access it within the application’s web root; the vulnerability does not provide directory listing or enumeration.