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10.0
Winter CMS allows attackers to gain higher user access
CVE-2026-27591
GHSA-pgpf-m8m4-6cg6
Summary
Authenticated Winter CMS users can upgrade their account access levels. To fix this, update to the latest version (1.0.477, 1.1.12, 1.2.12) or manually apply the security patches. If you can't update, manual patching is a temporary solution to prevent potential account access issues.
What to do
- Update winter wn-backend-module to version 1.2.12.
- Update winter wn-backend-module to version 1.1.12.
- Update winter wn-backend-module to version 1.0.477.
Affected software
| Vendor | Product | Affected versions | Fix available |
|---|---|---|---|
| winter | wn-backend-module | > 1.2.0 , <= 1.2.12 | 1.2.12 |
| winter | wn-backend-module | > 1.1.0 , <= 1.1.12 | 1.1.12 |
| winter | wn-backend-module | <= 1.0.477 | 1.0.477 |
Original title
Winter vulnerable to privilege escalation by authenticated backend users
Original 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.
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.
nvd CVSS3.1
9.9
Vulnerability type
CWE-284
Improper Access Control
CWE-639
Authorization Bypass Through User-Controlled Key
CWE-915
Published: 12 Mar 2026 · Updated: 13 Mar 2026 · First seen: 11 Mar 2026