Vulnerability · Published Mar 11, 2026 · Assigned by GitHub_M

CVE-2026-27591Winter: Privilege escalation by authenticated backend users

Critical 10.0

In plain English

A critical-severity improper access control in winter from wintercms. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 56% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)10.0Critical

Exploit odds (30 days)0.8%top 44.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Packagist	winter/wn-backend-module	1.2.12	GHSA-pgpf-m8m4-6cg6
Packagist	winter/wn-backend-module	1.1.12	GHSA-pgpf-m8m4-6cg6
Packagist	winter/wn-backend-module	1.0.477	GHSA-pgpf-m8m4-6cg6

Affected products (as reported)

Vendor	Product	Versions
wintercms	winter	>= 1.2.0, < 1.2.12>= 1.1.0, < 1.1.12< 1.0.477

Weakness: CWE-284, CWE-639, CWE-915 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

References

https://github.com/wintercms/winter/security/advisories/GHSA-pgpf-m8m4-6cg6 x_refsource_CONFIRM
https://wintercms.com/releases/v1.0.477 x_refsource_MISC
https://wintercms.com/releases/v1.1.12 x_refsource_MISC
https://wintercms.com/releases/v1.2.12 x_refsource_MISC