CVE-2026-27591 Winter: Privilege escalation by authenticated backend users
Authenticated backend users can escalate privileges by modifying their own roles and permissions via crafted requests.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-27591?
CVE-2026-27591 is a critical vulnerability in wintercms winter, published on 11 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Winter is a free, open-source content management system (CMS) based on the Laravel PHP framework. Prior to 1.0.477, 1.1.12, and 1.2.12, 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. This vulnerability is fixed in 1.0.477, 1.1.12, and 1.2.12.
Which versions are affected by CVE-2026-27591?
6 open source packages ship an affected version, including winter/wn-backend-module. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
winter/wn-backend-module Packagist | All versions | 1.0.477 |
winter/wn-backend-module Packagist | All versions | 1.0.477 |
winter/wn-backend-module Packagist | From 1.1.0 | 1.1.12 |
winter/wn-backend-module Packagist | From 1.1.0 | 1.1.12 |
winter/wn-backend-module Packagist | From 1.2.0 | 1.2.12 |
winter/wn-backend-module Packagist | From 1.2.0 | 1.2.12 |
Products include Wintercms Winter.
How do I fix CVE-2026-27591?
Upgrade winter/wn-backend-module to a fixed version for your release line: 1.0.477, 1.1.12 or 1.2.12.
Is CVE-2026-27591 being exploited?
There is no known exploitation of CVE-2026-27591 in the wild and no public exploit code.
Other vulnerabilities in wintercms winter
- CVE-2024-54149 Winter CMS Modules allows a sandbox bypass in Twig templates leading to data modification and deletion
- CVE-2022-39357 Winter vulnerable to Prototype Pollution in Snowboard framework
- CVE-2024-29686 Winter CMS Server-Side Template Injection (SSTI) vulnerability
- CVE-2023-52085 Winter CMS Local File Inclusion through Server Side Template Injection
- CVE-2023-52083 Stored XSS through privileged upload of Media Manager file followed by renaming
Sources
Also known as GHSA-pgpf-m8m4-6cg6.