Moodle: Improper Restriction of Excessive Authentication Attempts
CVE-2025-67853 is a high-severity improper restriction of excessive authentication attempts vulnerability in Moodle, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 4.1.22, 4.4.11, 4.5.8 as the first without the flaw, so updating Moodle to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.46% 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 Moodle to 4.1.22 or 4.4.11 or 4.5.8 or 5.0.4, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Moodle | Moodle | before 4.1.22; 4.4.0 up to, but not including, 4.4.11; 4.5.0 up to, but not including, 4.5.8; 5.0.0 up to, but not including, 5.0.4; 5.1.0 | 4.1.22, 4.4.11, 4.5.8, 5.0.4 |
Version data comes from NVD's product matching. 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
- NoneNo account or login is needed.
- 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
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by CNA (puiterwijk.org).
Official description
A flaw was found in Moodle. A remote attacker could exploit a lack of proper rate limiting in the confirmation email service. This vulnerability allows attackers to more easily enumerate or guess user credentials, facilitating brute-force attacks against user accounts.
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
Third-party and government advisories
- access.redhat.com/security/cve/CVE-2025-67853Third Party Advisory
- bugzilla.redhat.com/show_bug.cgi?id=2423847Third Party Advisory
Other vulnerabilities in Moodle
- 8.8 High severity
- 7.2 High severity
- 7.2 High severity
- 9.8 Critical severity
- 7.8 High severity
- 8.1 High severity
Recent Improper Restriction of Excessive Authentication Attempts vulnerabilities
- 9.8 Critical severity
- 9.4 Critical severity
- 7.5 High severity
- 9.8 Critical severity
- 9.1 Critical severity
- 8.1 High severity
Spotted an error? Tell us.