A vulnerability in multiple Atlassian products allows a remote, unauthenticated attacker to bypass Servlet Filters used by first and third party apps. The impact depends on which filters are used by each app, and how the filters are used. This vulnerability can result in authentication bypass and cross-site scripting. Atlassian has released updates that fix the root cause of this vulnerability, but has not exhaustively enumerated all potential consequences of this vulnerability. Atlassian Bamboo versions are affected before 8.0.9, from 8.1.0 before 8.1.8, and from 8.2.0 before 8.2.4. Atlassian Bitbucket versions are affected before 7.6.16, from 7.7.0 before 7.17.8, from 7.18.0 before 7.19.5, from 7.20.0 before 7.20.2, from 7.21.0 before 7.21.2, and versions 8.0.0 and 8.1.0. Atlassian Confluence versions are affected before 7.4.17, from 7.5.0 before 7.13.7, from 7.14.0 before 7.14.3, from 7.15.0 before 7.15.2, from 7.16.0 before 7.16.4, from 7.17.0 before 7.17.4, and version 7.21.0. Atlassian Crowd versions are affected before 4.3.8, from 4.4.0 before 4.4.2, and version 5.0.0. Atlassian Fisheye and Crucible versions before 4.8.10 are affected. Atlassian Jira versions are affected before 8.13.22, from 8.14.0 before 8.20.10, and from 8.21.0 before 8.22.4. Atlassian Jira Service Management versions are affected before 4.13.22, from 4.14.0 before 4.20.10, and from 4.21.0 before 4.22.4.