CVE-2024-33999Network attack vector

Unspecified impact via unsanitized MFA referrer

Published May 31, 2024 · Updated Aug 29, 2024

Improper input validation in Moodle LMS 4.3 through 4.3.3 allows attackers to cause unspecified impact via a crafted MFA referrer URL. The MFA entry point in admin/tool/mfa/index.php reads the HTTP_REFERER request header and uses its URL directly without the additional sanitization required for safe processing. Reaching the flaw requires a request through the MFA flow with an attacker-controlled referrer; Moodle has not disclosed the resulting operation or bounded consequence.

CVSS severity9.8
Critical
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Moodle LMS 4.3 through 4.3.3 allows attackers to cause unspecified impact via a crafted MFA referrer URL. The MFA entry point in admin/tool/mfa/index.php reads the HTTP_REFERER request header and uses its URL directly without the additional sanitization required for safe processing. Reaching the flaw requires a request through the MFA flow with an attacker-controlled referrer; Moodle has not disclosed the resulting operation or bounded consequence.

The record

CVE
CVE-2024-33999
Published
May 31, 2024
Updated
Aug 29, 2024
Vendor
Moodle
Product
Moodle LMS
Classifications
CWE-20
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 31, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 29, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.3 <=4.3.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Moodle · Moodle LMSversion=4.3 <=4.3.3

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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