CVE-2026-27591

Received Received - Intake

Privilege Escalation in Winter CMS via Role Modification

Publication date: 2026-03-11

Last updated on: 2026-03-19

Assigner: GitHub, Inc.

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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-03-11

Last Modified

2026-03-19

Generated

2026-07-06

AI Q&A

2026-03-12

EPSS Evaluated

2026-07-05

NVD

CVE-2026-27591

EUVD

EUVD-2026-11406

Affected Vendors & Products

Vendor	Product	Version / Range
wintercms	winter	to 1.0.477 (exc)
wintercms	winter	From 1.1.0 (inc) to 1.1.12 (exc)
wintercms	winter	From 1.2.0 (inc) to 1.2.12 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-284	The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
CWE-915	The product receives input from an upstream component that specifies multiple attributes, properties, or fields that are to be initialized or updated in an object, but it does not properly control which attributes can be modified.
CWE-639	The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

Attack-Flow Graph

Executive Summary

This vulnerability exists in Winter CMS, an open-source content management system based on the Laravel PHP framework. Before versions 1.0.477, 1.1.12, and 1.2.12, authenticated backend users could escalate their access level by modifying the roles or permissions assigned to their account. They could do this by sending specially crafted requests to the backend while logged in.

To exploit this vulnerability, an attacker must already have access to the backend with any level of user account. The vulnerability allows them to increase their privileges beyond what was originally assigned.

Impact Analysis

This vulnerability can have a severe impact because it allows an authenticated user to escalate their privileges to a higher access level within the Winter CMS backend.

An attacker with any backend access can gain full control over the system.
They can modify roles and permissions, potentially leading to unauthorized data access, data modification, or deletion.
The vulnerability has a high CVSS score of 9.9, indicating critical severity with high impact on confidentiality, integrity, and availability.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, you should upgrade Winter CMS to version 1.0.477, 1.1.12, or 1.2.12 or later, depending on your installed version series.

Ensure that only trusted users have backend access, as exploitation requires an authenticated backend user account.

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