NextcloudGHSA-48M7-7R2R-838RApplication specific tokens can change their own scope
8.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.5 High
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
0.002 Low
EPSS
Percentile
63.9%
Description
Impact
Nextcloud Server supports application specific tokens for authentication purposes. These tokens are supposed to be granted to a specific applications (e.g. DAV sync clients), and can also be configured by the user to not have any filesystem access.
Due to a lacking permission check, the tokens were however able to change their own permissions. Thus fileystem limited tokens were able to grant themselves access to the filesystem.
Patches
It is recommended that the Nextcloud Server is upgraded to 19.0.13, 20.0.11 or 21.0.3
Workarounds
None.
References
For more information
If you have any questions or comments about this advisory:
- Create a post in nextcloud/security-advisories
- Customers: Open a support ticket at support.nextcloud.com
| CPE | Name | Operator | Version |
|---|---|---|---|
| nextcloud server | lt | 19.0.13 | |
| nextcloud server | lt | 20.0.11 | |
| nextcloud server | lt | 21.0.3 |
Related
8.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.5 High
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
0.002 Low
EPSS
Percentile
63.9%