What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-11 · updated 2026-06-17
• Weakness: CWE-284

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 products

• wintercms winter: before 1.0.477; from 1.1.0 before 1.1.12; from 1.2.0 before 1.2.12 — fixed in 1.0.477, 1.1.12, 1.2.12

How to fix

Upgrade to a fixed version: wintercms winter 1.0.477, 1.1.12, 1.2.12. Check the vendor advisory for mitigations.

References

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

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