Nextcloud server is an open source home cloud platform. Affected versions of Nextcloud stored OAuth2 tokens in plaintext which allows an attacker who has gained access to the server to potentially elevate their privilege. This issue has been addressed and users are recommended to upgrade their Nextcloud Server to version 25.0.8, 26.0.3 or 27.0.1. There are no known workarounds for this vulnerability.
The product stores sensitive information in cleartext within a resource that might be accessible to another control sphere.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Nextcloud_server | Nextcloud | 25.0.0 (including) | 25.0.8 (excluding) |
| Nextcloud_server | Nextcloud | 26.0.0 (including) | 26.0.3 (excluding) |
| Nextcloud_server | Nextcloud | 27.0.0 (including) | 27.0.0 (including) |
Because the information is stored in cleartext (i.e., unencrypted), attackers could potentially read it. Even if the information is encoded in a way that is not human-readable, certain techniques could determine which encoding is being used, then decode the information. When organizations adopt cloud services, it can be easier for attackers to access the data from anywhere on the Internet. In some systems/environments such as cloud, the use of “double encryption” (at both the software and hardware layer) might be required, and the developer might be solely responsible for both layers, instead of shared responsibility with the administrator of the broader system/environment.