CVE-2021-43724Public exploitNetwork attack vector

Stored browser script execution via active SVG upload

Published Feb 23, 2022 · Updated Aug 4, 2024

Stored cross-site scripting in Subrion CMS 4.2.1 and earlier allows remote authenticated users to run script in visitors' browsers. The Create Page editor accepts an SVG containing an onload handler through its image upload workflow and publishes a page that serves the active script without neutralization. Administrator access is required to create the page, and a victim must open the resulting page; the script can steal accessible session cookies or redirect the browser.

CVSS severity4.8
Medium
EPSS probability0.49%
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 Subrion CMS 4.2.1 and earlier allows remote authenticated users to run script in visitors' browsers. The Create Page editor accepts an SVG containing an onload handler through its image upload workflow and publishes a page that serves the active script without neutralization. Administrator access is required to create the page, and a victim must open the resulting page; the script can steal accessible session cookies or redirect the browser.

The record

CVE
CVE-2021-43724
Published
Feb 23, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Feb 23, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
4.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

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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