security-advisories: Improper Access Control
CVE-2023-30539 is a high-severity improper access control vulnerability in security-advisories from Nextcloud, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected security-advisories versions: Nextcloud Server: < 24.0.11; Nextcloud Server: >= 25.0.0, < 25.0.5; Nextcloud Files automated tagging: >= 1.11.0, < 1.11.1, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.63% chance of exploitation within 30 days, higher than 51% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Nextcloud Files Automated Tagging to 1.14.2 or 1.15.3, whichever matches your release line, or a later version.
- Update Nextcloud Server to 21.0.9.11 or 22.2.10.11 or 23.0.12.6 or 24.0.11, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Nextcloud | security-advisories | Nextcloud Server: < 24.0.11; Nextcloud Server: >= 25.0.0, < 25.0.5; Nextcloud Files automated tagging: >= 1.11.0, < 1.11.1; Nextcloud Files automated tagging: >= 1.12.0, < 1.12.1; Nextcloud Files automated tagging: >= 1.13.0, < 1.13.1; Nextcloud Files automated tagging: >= 1.14.0, < 1.14.2; Nextcloud Files automated tagging: >= 1.15.0, < 1.15.3; Nextcloud Files automated tagging: >= 1.16.0, < 1.16.1 | Not stated |
| Nextcloud | Nextcloud Files Automated Tagging | 1.14.0 up to, but not including, 1.14.2; 1.15.0 up to, but not including, 1.15.3; 1.11.0; 1.12.0; 1.13.0; 1.16.0 | 1.14.2, 1.15.3 |
| Nextcloud | Nextcloud Server | 21.0.0 up to, but not including, 21.0.9.11; 22.0.0 up to, but not including, 22.2.10.11; 23.0.0 up to, but not including, 23.0.12.6; 24.0.0 up to, but not including, 24.0.11; 25.0.0 up to, but not including, 25.0.5 | 21.0.9.11, 22.2.10.11, 23.0.12.6, 24.0.11, 25.0.5 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 6.5 | Medium | CNA (github.com) |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
Nextcloud is a personal home server system. Depending on the set up tags and other workflows this issue can be used to limit access of others or being able to grant them access when there are system tag based files access control or files retention rules. It is recommended that the Nextcloud Server is upgraded to 24.0.11 or 25.0.5, the Nextcloud Enterprise Server to 21.0.9.11, 22.2.10.11, 23.0.12.6, 24.0.11 or 25.0.5, and the Nextcloud Files automated tagging app to 1.11.1, 1.12.1, 1.13.1, 1.14.2, 1.15.3 or 1.16.1. Users unable to upgrade should disable all workflow related apps. Users are advised to upgrade.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Access Control
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
How developers prevent this class of flaw
- Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
- hackerone.com/reports/1895976Permissions Required
Other vulnerabilities in security-advisories
- 7.1 High severity
- 8.2 High severity
- 8.8 High severity
- 8.1 High severity
- 8.1 High severity
Recent Improper Access Control vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 8.1 High severity
- 7.8 High severity
- 7.5 High severity
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