Impact
Authenticated users can inject malicious code in widgets with units, which is then executed both in the element preview (back end) and on the website (front end).
Patches
Update to Contao 4.9.42, 4.13.28 or 5.1.10.
Workarounds
Disable login for all untrusted back end users.
References
https://contao.org/en/security-advisories/cross-site-scripting-in-widgets-with-units
For more information
If you have any questions or comments about this advisory, open an issue in contao/contao.
Credits
Thanks to Christian Pöschl and Fabian Brenner from usd AG for reporting this vulnerability.
Impact
If the crawler is set to crawl protected pages, it sends the cookie header to externals URLs.
Patches
Update to Contao 4.13.40 or 5.3.4.
Workarounds
Disable crawling protected pages.
References
https://contao.org/en/security-advisories/session-cookie-disclosure-in-the-crawler
For more information
If you have any questions or comments about this advisory, open an issue in contao/contao.
Impact
It is possible to inject insert tags via the form generator if the submitted form data is output on the page in a specific way.
Patches
Update to Contao 4.13.40 or 5.3.4.
Workarounds
Do not output the submitted form data on the website.
References
https://contao.org/en/security-advisories/insert-tag-injection-via-the-form-generator
For more information
If you have any questions or comments about this advisory, open an issue in contao/contao.
Impact
Users can insert malicious code into file names when uploading files, which is then executed in tooltips and popups in the backend.
Patches
Update to Contao 4.13.40 or Contao 5.3.4.
Workarounds
Disable uploads for untrusted users.
References
https://contao.org/en/security-advisories/cross-site-scripting-in-the-file-manager
For more information
If you have any questions or comments about this advisory, open an issue in contao/contao.
Credits
Thanks to Alexander Wuttke for reporting this vulnerability.
Impact
If BBCode is enabled for comments, users can inject CSS styles.
Patches
Update to Contao 4.13.40 or 5.3.4.
Workarounds
Disable BBCode for comments.
References
https://contao.org/en/security-advisories/insufficient-bbcode-sanitization
For more information
If you have any questions or comments about this advisory, open an issue in contao/contao.
Contao is an open source content management system. Prior to versions 4.9.40, 4.13.21, and 5.1.4, logged in users can list arbitrary system files in the file manager by manipulating the Ajax request. However, it is not possible to read the contents of these files. Users should update to Contao 4.9.40, 4.13.21 or 5.1.4 to receive a patch. There are no known workarounds.
Impact
Back end users with access to the file manager can upload malicious files and execute them on the server.
Patches
Update to Contao 4.13.49, 5.3.15 or 5.4.3.
Workarounds
Configure your web server so it does not execute PHP files and other scripts in the Contao file upload directory.
References
https://contao.org/en/security-advisories/remote-command-execution-through-file-uploads
For more information
If you have any questions or comments about this advisory, open an issue in contao/contao.
Credits
Thanks to Jakob Steeg from usd AG for reporting this vulnerability.