Moodle up to 5.1.0 Confirmation Email Service excessive authentication

Summaryinfo

A vulnerability was found in Moodle up to 4.1.21/4.4.11/4.5.7/5.0.3/5.1.0. It has been rated as problematic. Affected by this vulnerability is an unknown functionality of the component Confirmation Email Service. Performing a manipulation results in excessive authentication. This vulnerability is cataloged as CVE-2025-67853. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Moodle up to 4.1.21/4.4.11/4.5.7/5.0.3/5.1.0. It has been classified as problematic. This affects an unknown function of the component Confirmation Email Service. The manipulation with an unknown input leads to a excessive authentication vulnerability. CWE is classifying the issue as CWE-307. The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame, making it more susceptible to brute force attacks. This is going to have an impact on confidentiality. The summary by CVE is:

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.

It is possible to read the advisory at access.redhat.com. This vulnerability is uniquely identified as CVE-2025-67853 since 12/12/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/07/2026). The attack technique deployed by this issue is T1110.001 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 297886 (Linux Distros Unpatched Vulnerability : CVE-2025-67853), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.1.22, 4.4.12, 4.5.8, 5.0.4 or 5.1.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (297886). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Learning Management Software

Name

• Moodle

Version

• 4.1.0
• 4.1.1
• 4.1.2
• 4.1.3
• 4.1.4
• 4.1.5
• 4.1.6
• 4.1.7
• 4.1.8
• 4.1.9
• 4.1.10
• 4.1.11
• 4.1.12
• 4.1.13
• 4.1.14
• 4.1.15
• 4.1.16
• 4.1.17
• 4.1.18
• 4.1.19
• 4.1.20
• 4.1.21
• 4.4.0
• 4.4.1
• 4.4.2
• 4.4.3
• 4.4.4
• 4.4.5
• 4.4.6
• 4.4.7
• 4.4.8
• 4.4.9
• 4.4.10
• 4.4.11
• 4.5.0
• 4.5.1
• 4.5.2
• 4.5.3
• 4.5.4
• 4.5.5
• 4.5.6
• 4.5.7
• 5.0
• 5.0.0
• 5.0.1
• 5.0.2
• 5.0.3
• 5.1.0

License

• open-source

Website

• Product: https://moodle.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

Discussion