CVE-2021-21340Network attack vector

Stored cross-site scripting via descriptionColumn previews

Published Mar 23, 2021 · Updated Aug 3, 2024

Stored cross-site scripting in TYPO3 CMS 10.0.0 through 10.4.13 and 11.0.0 through 11.1.0 allows remote authenticated users to run script. The content preview renderer places attacker-controlled descriptionColumn database-field content into the page module preview without proper output neutralization. Exploitation requires a valid backend account and a user to preview the crafted field, allowing script to act with that viewer's backend browser access.

CVSS severity5.4
Medium
EPSS probability0.87%
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 TYPO3 CMS 10.0.0 through 10.4.13 and 11.0.0 through 11.1.0 allows remote authenticated users to run script. The content preview renderer places attacker-controlled descriptionColumn database-field content into the page module preview without proper output neutralization. Exploitation requires a valid backend account and a user to preview the crafted field, allowing script to act with that viewer's backend browser access.

The record

CVE
CVE-2021-21340
Published
Mar 23, 2021
Updated
Aug 3, 2024
Vendor
in2code GmbH
Product
TYPO3 CMS
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 23, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=>= 10.0.0, <= 10.4.13
  2. Affected versionversion=>= 11.0.0, <= 11.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

in2code GmbH · TYPO3 CMSversion=>= 10.0.0, <= 10.4.13; version=>= 11.0.0, <= 11.1.0

Published CVSS scores

3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
5.0TYPO3CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC:C

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')
T1059.007Command and Scripting Interpreter: JavaScript/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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