security-advisories: Improper Restriction of Excessive Authentication Attempts
CVE-2023-25818 is a high-severity improper restriction of excessive authentication attempts vulnerability in security-advisories from Nextcloud, with a CVSS 3.1 base score of 7.1 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: >= 24.0.0, < 24.0.10; >= 25.0.0, < 25.0.4. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.6% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Nextcloud Server to 21.0.9.10 or 22.2.10.10 or 23.0.12.5 or 24.0.10, 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 | >= 24.0.0, < 24.0.10; >= 25.0.0, < 25.0.4 | Not stated |
| Nextcloud | Nextcloud Server | 21.0.0 up to, but not including, 21.0.9.10; 22.0.0 up to, but not including, 22.2.10.10; 23.0.0 up to, but not including, 23.0.12.5; 24.0.0 up to, but not including, 24.0.10; 25.0.0 up to, but not including, 25.0.4 | 21.0.9.10, 22.2.10.10, 23.0.12.5, 24.0.10, 25.0.4 |
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
- LowSome restricted data can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 5.3 | Medium | CNA (github.com) |
| CVSS 3.1 | 7.1 | High | NVD |
Official description
Nextcloud server is an open source, personal cloud implementation. In affected versions a malicious user could try to reset the password of another user and then brute force the 62^21 combinations for the password reset token. As of commit `704eb3aa` password reset attempts are now throttled. Note that 62^21 combinations would significant compute resources to brute force. None the less it is recommended that the Nextcloud Server is upgraded to 24.0.10 or 25.0.4. There are no known workarounds for this vulnerability.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Restriction of Excessive Authentication Attempts
The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.
How developers prevent this class of flaw
- Common protection mechanisms include: Disconnecting the user after a small number of failed attempts Implementing a timeout Locking out a targeted account Requiring a computational task on the user's part.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator.
More Improper Restriction of Excessive Authentication Attempts vulnerabilities (CWE-307)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
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 Restriction of Excessive Authentication Attempts vulnerabilities
- 9.8 Critical severity
- 7.8 High severity
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
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