CVE-2021-4072Network attack vector

Stored script execution via unsanitized report URL

Published Dec 24, 2021 · Updated Aug 3, 2024

Stored cross-site scripting in Elgg Foundation Elgg before 3.3.24 allows remote authenticated users to execute script via a report URL. The reportedcontent add action stores the supplied address directly in ElggReportedContent instead of normalizing the URL before persistence. Exploitation requires report-submission access and another user to view the stored entry, allowing script to act in that viewer's browser context.

CVSS severity5.4
Medium
EPSS probability0.70%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in Elgg Foundation Elgg before 3.3.24 allows remote authenticated users to execute script via a report URL. The reportedcontent add action stores the supplied address directly in ElggReportedContent instead of normalizing the URL before persistence. Exploitation requires report-submission access and another user to view the stored entry, allowing script to act in that viewer's browser context.

The record

CVE
CVE-2021-4072
Published
Dec 24, 2021
Updated
Aug 3, 2024
Vendor
Elgg Foundation
Product
Elgg
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 24, 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=unspecified <3.3.24

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Elgg Foundation · Elggversion=unspecified <3.3.24

Published CVSS scores

5.4GitLab Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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')
T1203Exploitation for Client Execution

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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