XSS vulnerability in Activity Stream gadget

We have identified and fixed a cross-site scripting (XSS) vulnerability in the Confluence Activity Stream gadget. All versions from 3.1 to 3.4.6 are affected.

XSS vulnerabilities potentially allow an attacker to embed their own JavaScript into a Confluence page. You can read more about XSS attacks at various places on the web, including these:

• cgisecurity.com: http://www.cgisecurity.com/articles/xss-faq.shtml
• The Web Application Security Consortium: http://projects.webappsec.org/Cross-Site+Scripting

This issue is reported in our security advisory on this page:
https://confluence.atlassian.com/x/MgCzDQ

The page also includes detailed patch instructions.