Answer in brief
CVE-2026-54256 records a Medium severity (CVSS 5.4) vulnerability in Winter: Authenticated IDOR in backend FileUpload widget allows cross-user access to attachment metadata. The current sources do not mark it as known exploited. The current feed maps winter/wn-backend-module (composer), wintercms/winter (generic), winter/wn-backend-module (packagist). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps winter/wn-backend-module (composer), wintercms/winter (generic), winter/wn-backend-module (packagist). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| winter/wn-backend-modulecomposer | <=1.2.12 | 1.2.13 |
| wintercms/wintergeneric | < 1.2.13 | Not reported |
| winter/wn-backend-modulepackagist | >=0 <1.2.13 | 1.2.13 |
Published upstream
Aug 26, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 20, 2026
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.
Quoted source text, attributed separately from HOL analysis.