GitHub Advisoryadvisory · Packagist

GHSA-pgpf-m8m4-6cg6 Winter vulnerable to privilege escalation by authenticated backend users

CRITICAL Published 2026-03-12 Modified 2026-03-12 Official page ↗
Aliases
CVE-2026-27591
Ecosystem
Packagist
Packages
winter/wn-backend-module
Severity
Critical
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Weaknesses
CWE-284, CWE-639, CWE-915
Reviewed
2026-03-12

Affected packages

• Packagist winter/wn-backend-module: >= 1.2.0, < 1.2.12 → fixed in 1.2.12 • Packagist winter/wn-backend-module: >= 1.1.0, < 1.1.12 → fixed in 1.1.12 • Packagist winter/wn-backend-module: < 1.0.477 → fixed in 1.0.477

Description

Impact Affected versions of Winter CMS allowed authenticated backend users to escalate their accounts level of access to the system by modifying the roles / permissions assigned to their account through specially crafted requests to the backend while logged in. To actively exploit this security issue, an attacker would need access to the Backend with a user account with any level of access. The Winter CMS maintainers strongly recommend that all Winter CMS sites that have any reliance on the roles & permissions system to update immediately. Security fixes have been backported to all major versions of Winter (1.0, 1.1, and 1.2). Patches Multiple fixes and defence in depth has been applied to prevent current and future privilege escalation attacks at the lowest level possible. This security issue has been fixed as of https://wintercms.com/releases/v1.0.477, https://wintercms.com/releases/v1.1.12, https://wintercms.com/releases/v1.2.12. Workarounds If you cannot upgrade, you may apply the changes from the releases to your Winter CMS installation manually to resolve this issue.

Related

Alias · CVE (1)

  • CVE-2026-27591 Winter is a free, open-source content management system (CMS) based on the Laravel PHP framework. vulnerability

Weakness · CWE (3)

  • CWE-284 Improper Access Control weakness
  • CWE-639 Authorization Bypass Through User-Controlled Key weakness
  • CWE-915 Improperly Controlled Modification of Dynamically-Determined Object Attributes weakness

References