---
id: CVE-2026-54256
title: Winter CMS is a content management system built on the Laravel PHP framework
summary: >-
  Winter CMS is a content management system built on the Laravel PHP framework.
  In versions up to and including 1.2.12, the backend FileUpload form widget
  trusted an attacker-controlled file_id POST parameter when resolving the
  attachment …
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N'
cwe:
  - CWE-284
  - CWE-639
vendor: winter
product: winter/wn-backend-module
affected:
  - winter/wn-backend-module <= 1.2.12
patched:
  - winter/wn-backend-module 1.2.13
published: '2026-08-26'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:09:13.080'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-54256'
references:
  - url: >-
      https://github.com/wintercms/winter/commit/9cb0ae5f9d837db141ab111c6a7de8eed9603d25
    label: security-advisories@github.com
  - url: >-
      https://github.com/wintercms/winter/security/advisories/GHSA-3277-h8g9-qj5f
    label: security-advisories@github.com
  - url: >-
      https://github.com/wintercms/winter/security/advisories/GHSA-qq9m-vfv4-pj5w
  - url: 'https://github.com/wintercms/winter/releases/tag/v1.2.13'
  - url: 'https://github.com/advisories/GHSA-3277-h8g9-qj5f'
tags:
  - nvd
  - ghsa
  - composer
epss: 0.00143
epssPercentile: 0.04003
aliases:
  - GHSA-3277-h8g9-qj5f
ecosystem: composer
ingestedAt: '2026-08-20T18:59:54.594Z'
---

## Overview

Winter CMS is a content management system built on the Laravel PHP framework. In versions up to and including 1.2.12, the backend FileUpload form widget trusted an attacker-controlled file_id POST parameter when resolving the attachment it operates on, allowing an authenticated backend user to read and modify attachment records belonging to other users or records. The widget's getFileRecord() lookup resolved the posted id against the global system_files table without verifying that the file belonged to the widget's own relation, parent record, or deferred-binding session. Because all attachments share a single File model and table and attachment ids are sequential integers that are easily enumerated, a user reaching any form with a fileupload field, including the built-in My Account avatar field that requires no specific permission, could target arbitrary attachments to modify their title and description via onSaveAttachmentConfig and change their sort order via onSortAttachments, which passed posted ids straight to an unscoped update. CSRF tokens remain enforced, so exploitation requires a valid authenticated backend session with any level of access. This issue is fixed in version 1.2.13.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-54256)

Affected packages:

- `winter/wn-backend-module <= 1.2.12`

Patched in:

- `winter/wn-backend-module 1.2.13`

Source: https://github.com/advisories/GHSA-3277-h8g9-qj5f