VDB-222426 · CVE-2021-36402 · EUVD-2023-1016

Moodle Account Confirmation Email input validation

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.8	$5k-$25k	0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in Moodle. The affected element is an unknown function of the component Account Confirmation Email Handler. The manipulation results in input validation. This vulnerability is identified as CVE-2021-36402. The attack can be executed remotely. There is not any exploit available. VulDB is the best source for vulnerability data and more expert information about this specific topic.

Detailsinfo

A vulnerability classified as critical has been found in Moodle (Learning Management Software) (affected version unknown). Affected is an unknown functionality of the component Account Confirmation Email Handler. The manipulation with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In Moodle, Users' names required additional sanitizing in the account confirmation email, to prevent a self-registration phishing risk.

The weakness was released 03/07/2023. The advisory is available at moodle.org. This vulnerability is traded as CVE-2021-36402 since 07/12/2021. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 07/06/2025).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2023-1016). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

Learning Management Software

Name

Moodle

License

open-source

Website

Product: https://moodle.org/

CPE 2.3info

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CPE 2.2info

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CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.8
VulDB Meta Temp Score: 5.8

VulDB Base Score: 6.3
VulDB Temp Score: 6.3
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 5.3
NVD Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Input validation
CWE: CWE-20
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔍

Timelineinfo

07/12/2021 🔍
03/07/2023 +603 days 🔍
03/07/2023 +0 days 🔍
07/06/2025 +852 days 🔍

Sourcesinfo

Product: moodle.org

Advisory: moodle.org
Status: Confirmed

CVE: CVE-2021-36402 (🔍)
GCVE (CVE): GCVE-0-2021-36402
GCVE (VulDB): GCVE-100-222426
EUVD: 🔍

Entryinfo

Created: 03/07/2023 08:14 AM
Updated: 07/06/2025 04:46 PM
Changes: 03/07/2023 08:14 AM (36), 03/07/2025 09:39 PM (26), 07/06/2025 04:46 PM (1)
Complete: 🔍
Cache ID: 244:3CE:40