A clickjacking attack can be achieved for users of Internet Explorer or Edge
Impact
An attacker could trick a user into doing some actions like clicking on a button or filling a form and route informations to another page.
CVSSv3 score: 5.4 (CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N)
Exploitation
Clickjacking protection added in request #7785 can be bypassed for IE Edge users. This is due to the fact that IE/Edge does not support the CSP level 2 directive frame-ancestors and that Tuleap have multiple ways for an user to create a frame to untrusted pages (sidebar service, PHPWiki transclude plugin...).
The only protection left for IE/Edge users is the X-Frame-Options header that Tuleap currently sets to SAMEORIGIN. It can be bypassed when arbitrary frames are created. Indeed, it does not prevent the inclusion when from origin A (Tuleap) an unstrusted content from origin B is included that itself includes a resource from origin A (and thus allowing the clickjacking attack).
References
CWE-693
OWASP - Clickjacking
Exploiting the unexploitable with lesser known browser tricks by @filedescriptor
RFC7034 - HTTP Header Field X-Frame-Options