Collabora Online is a collaborative online office suite based on LibreOffice technology. This vulnerability report describes a reflected XSS vulnerability with full CSP bypass in Nextcloud installations using the recommended bundle. The vulnerability can be exploited to perform a trivial account takeover attack. The vulnerability allows attackers to inject malicious code into web pages, which can be executed in the context of the victim's browser session. This means that an attacker can steal sensitive data, such as login credentials or personal information, or perform unauthorized actions on behalf of the victim, such as modifying or deleting data. In this specific case, the vulnerability allows for a trivial account takeover attack. An attacker can exploit the vulnerability to inject code into the victim's browser session, allowing the attacker to take over the victim's account without their knowledge or consent. This can lead to unauthorized access to sensitive information and data, as well as the ability to perform actions on behalf of the victim. Furthermore, the fact that the vulnerability bypasses the Content Security Policy (CSP) makes it more dangerous, as CSP is an important security mechanism used to prevent cross-site scripting attacks. By bypassing CSP, attackers can circumvent the security measures put in place by the web application and execute their malicious code. This issue has been patched in versions 22.05.13, 21.11.9, and 6.4.27. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Collabora Online is a collaborative online office suite based on LibreOffice technology. Each document in Collabora Online is opened by a separate "Kit" instance in a different "jail" with a unique directory "jailID" name. For security reasons, this directory name is randomly generated and should not be given out to the client. In affected versions of Collabora Online it is possible to use the CELL() function, with the "filename" argument, in the spreadsheet component to get a path which includes this JailID. The impact of this vulnerability in its own is low because it requires to be chained with another vulnerability. Users should upgrade to Collabora Online 23.05.9; Collabora Online 22.05.22; Collabora Online 21.11.10 or higher. There are no known workarounds for this vulnerability.