How severe is CVE-2026-56381?

No CVSS score has been assigned to CVE-2026-56381 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-56381?

CVE-2026-56381 affects the following packages: craftcms/cms (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-56381?

Update craftcms/cms to 5.8.22 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-56381 is resolved across your whole dependency graph.

How do I detect CVE-2026-56381 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for craftcms/cms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-56381 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2026-56381 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-56381 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-56381?

CVE-2026-56381 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 8th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-56381?

CVE-2026-56381 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-56381 published, and has it been updated?

CVE-2026-56381 was published on June 21, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

CVE-2026-56381 — cms

CVE-2026-56381 is a Cross-site Scripting (XSS) vulnerability in craftcms/cms. A fix is available for craftcms/cms — see the affected versions and patch details below.

Craft CMS - Stored XSS via User Group Name in User Permissions Page

Also known asGHSA-g3hp-vvqf-8vw6

Published

Jun 21, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-56381.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs8th percentile — riskier than 8% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐘craftcms/cms

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Summary

A stored XSS vulnerability exists in the User Permissions page. The User Group name is rendered without proper HTML escaping in the permissions section, allowing an attacker to execute arbitrary JavaScript when another user views or edits a user's permissions.

[!NOTE] This is a separate vulnerability from the previously reported "Stored XSS via User Group Name in User Settings Page" and "Multiple Stored XSS in User Group Edit Page". This affects a different sink: the individual user's permissions page.

Proof of Concept

Required Permissions

Admin access
allowAdminChanges is enabled in production, which is against our security recommendations.

Steps to Reproduce

Log in to the control panel as an admin
Navigate to Settings → Users → User Groups
Create or edit a user group and set the Name field to:
```
<img src=x onerror="alert('XSS')" hidden>
```
Save the user group
Navigate to Users and edit any user (/admin/users/{id})
Click on the Permissions tab
XSS executes

Mitigation

Sanitize user group names when rendering in the user permissions template.

References

https://github.com/craftcms/cms-ghsa-4mgv-366x-qxvx/pull/2

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`craftcms/cms`	≥ 5.0.0-RC1&&< 5.8.22	5.8.22`composer require craftcms/cms:^5.8.22`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for craftcms/cms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update craftcms/cms to 5.8.22 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-56381 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

## Summary A stored XSS vulnerability exists in the User Permissions page. The User Group name is rendered without proper HTML escaping in the permissions section, allowing an attacker to execute arbitrary JavaScript when another user views or edits a user's permissions. > [!NOTE] > This is a separate vulnerability from the previously reported "[Stored XSS via User Group Name in User Settings Page](https://github.com/craftcms/cms/security/advisories/GHSA-2423-8xxj-wc3g)" and "[Multiple Stored XSS in User Group Edit Page](https://github.com/craftcms/cms/security/advisories/GHSA-vx7g-xw92-g4xj)

O3 Security · Impact-Aware SCA

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