Improper Encoding or Escaping of Output Affecting craftcms/cms package, versions >=4.15.3, <4.17.3>=5.7.5, <5.9.7
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published11 Mar 2026
- disclosed11 Mar 2026
- creditUnknown
Introduced: 11 Mar 2026
NewCVE-2026-31859 (opens in a new tab)How to fix?
Upgrade craftcms/cms to version 4.17.3, 5.9.7 or higher.
Overview
craftcms/cms is a content management system.
Affected versions of this package are vulnerable to Improper Encoding or Escaping of Output via the setReturnUrl function. An attacker can execute arbitrary JavaScript in the context of the application by supplying a crafted return URL containing a malicious scheme such as javascript: or data:. This can lead to session hijacking, data exfiltration, phishing, or performing actions on behalf of the authenticated user when the malicious URL is rendered in an href attribute.