Is This vulnerability exploited in the wild?

No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

How severe is This vulnerability?

Low severity, with a CVSS score of 2.1, published 10 April 2026.

Which products and versions are affected?

redaxo/source (Packagist) < 5.21.0; REDAXO CMS < 5.21.0.

Is there a fix for This vulnerability?

A patch was published on 2026-04-09: Version 5.21.0 released. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is This vulnerability attacked?

It is attacked over the network, in a web application.

Check whether you run redaxo/source (Packagist) or REDAXO CMS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

REDAXO CMS reflected XSS in backend Metainfo API

Q: Is there a fix for This vulnerability?

A patch was published on 2026-04-09: Version 5.21.0 released. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is This vulnerability attacked?

It is attacked over the network, in a web application.

Q: Am I affected?

Check whether you run redaxo/source (Packagist) or REDAXO CMS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Severity: low · CVSS 2.1 · Published 2026-04-10

REDAXO CMS, a popular content management system, contains a security flaw in its administrative backend. An attacker could potentially execute malicious scripts in the browser of a logged-in administrator. While this could lead to unauthorized actions or data theft within the management interface, the attack is difficult to perform because it requires the attacker to possess a valid security token (CSRF token) and high-level access privileges.

Technologies: redaxo/source (Packagist), REDAXO CMS. Vendors: Packagist, REDAXO.

Quick answers

Is This vulnerability exploited in the wild?: No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
How severe is This vulnerability?: Low severity, with a CVSS score of 2.1, published 10 April 2026.
Which products and versions are affected?: redaxo/source (Packagist) < 5.21.0; REDAXO CMS < 5.21.0.
Is there a fix for This vulnerability?: A patch was published on 2026-04-09: Version 5.21.0 released. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is This vulnerability attacked?: It is attacked over the network, in a web application.
Am I affected?: Check whether you run redaxo/source (Packagist) or REDAXO CMS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A reflected cross-site scripting (XSS) vulnerability exists in the REDAXO backend within the Metainfo API handler. The 'type' GET parameter is retrieved in 'redaxo/src/addons/metainfo/lib/handler/api_default_fields.php' and concatenated into a 'rex_api_exception' message. This message is subsequently rendered by 'rex_view::error()' and 'rex_view::message()' without proper HTML escaping, allowing for script injection. Exploitation requires the attacker to be authenticated to the backend with high privileges and to include a valid '_csrf_token' in the request. The vulnerability is patched in version 5.21.0.

Affected products

REDAXO REDAXO CMS < 5.21.0

Timeline

2026-04-09: patched: Version 5.21.0 released.
2026-04-10: advisory

References

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