CVE-2021-36788Network attack vector

Authenticated XSS via unencoded preview and structured data

Published Aug 13, 2021 · Updated Aug 4, 2024

Cross-site scripting in Yoast SEO for TYPO3 7.2.2 and earlier allows remote authenticated users to execute script in HTML output. PreviewService decodes title and meta-description entities without stripping tags, while structured-data output permits a closing script sequence and client actions pass title and description content without tag removal. A TYPO3 backend account is required; crafted content can execute in the application origin and expose or alter data accessible to the viewing session.

CVSS severity5.4
Medium
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Yoast SEO for TYPO3 7.2.2 and earlier allows remote authenticated users to execute script in HTML output. PreviewService decodes title and meta-description entities without stripping tags, while structured-data output permits a closing script sequence and client actions pass title and description content without tag removal. A TYPO3 backend account is required; crafted content can execute in the application origin and expose or alter data accessible to the viewing session.

The record

CVE
CVE-2021-36788
Published
Aug 13, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, CAPEC-63, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 13, 2021CVE 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

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

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

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
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
5.4GitHub 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')
CAPEC-63Cross-Site Scripting (XSS)
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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