Nextcloud Server before 9.0.52 & ownCloud Server before 9.0.4 are vulnerable to a log pollution vulnerability potentially leading to a local XSS. The download log functionality in the admin screen is delivering the log in JSON format to the end-user. The file was delivered with an attachment disposition forcing the browser to download the document. However, Firefox running on Microsoft Windows would offer the user to open the data in the browser as an HTML document. Thus any injected data in the log would be executed.
The product generates an error message that includes sensitive information about its environment, users, or associated data.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Nextcloud_server | Nextcloud | * | 9.0.52 (excluding) |
| Owncloud | Owncloud | * | 9.0.4 (excluding) |
| Owncloud | Ubuntu | precise | * |
The sensitive information may be valuable information on its own (such as a password), or it may be useful for launching other, more serious attacks. The error message may be created in different ways:
An attacker may use the contents of error messages to help launch another, more focused attack. For example, an attempt to exploit a path traversal weakness (CWE-22) might yield the full pathname of the installed application. In turn, this could be used to select the proper number of “..” sequences to navigate to the targeted file. An attack using SQL injection (CWE-89) might not initially succeed, but an error message could reveal the malformed query, which would expose query logic and possibly even passwords or other sensitive information used within the query.