CVE-2021-20279Network attack vector

Stored XSS via unsanitized profile ID number

Published Mar 15, 2021 · Updated Aug 3, 2024

Stored XSS in Moodle LMS before 3.10.2, 3.9.5, 3.8.8, or 3.5.17 allows remote authenticated users to inject script through profile ID numbers. The profile ID number field stores insufficiently sanitized input and later renders it as active browser content in another user's session. An authenticated account must save a crafted ID number and another user must view the affected profile output, allowing script execution in that viewer's browser context.

CVSS severity5.4
Medium
EPSS probability1.00%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Moodle LMS before 3.10.2, 3.9.5, 3.8.8, or 3.5.17 allows remote authenticated users to inject script through profile ID numbers. The profile ID number field stores insufficiently sanitized input and later renders it as active browser content in another user's session. An authenticated account must save a crafted ID number and another user must view the affected profile output, allowing script execution in that viewer's browser context.

The record

CVE
CVE-2021-20279
Published
Mar 15, 2021
Updated
Aug 3, 2024
Vendor
Moodle
Product
Moodle LMS
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=Fixed in 3.10.2, 3.9.5, 3.8.8, 3.5.17

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Moodle · Moodle LMSversion=Fixed in 3.10.2, 3.9.5, 3.8.8, 3.5.17

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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