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Winter: My Account preview exposes another backend user's profile by record ID

Moderate severity GitHub Reviewed Published Aug 19, 2026 in wintercms/winter • Updated Aug 20, 2026

Package

composer winter/wn-backend-module (Composer)

Affected versions

= 1.2.13

Patched versions

1.2.14

Description

Impact

Backend\Controllers\MyAccount, introduced in v1.2.13, declares an empty $requiredPermissions array so that any authenticated backend user can manage their own account. It implements the FormController behavior, which exposes three routable actions — create, update and preview — that each take a record id from the URL.

index() passes the authenticated user's own id to the behavior, but the inherited actions were left routable and formFindModelObject() was not scoped, so a caller-supplied id resolved against an unscoped Backend\Models\User query:

GET /backend/backend/myaccount/preview/{other_user_id}

preview disclosed the target user's first name, last name, login, email address and avatar; update was equally routable and additionally disclosed role, group membership, superuser flag and throttle state. Password controls render a mask, so no credential material was exposed. Backend user ids are sequential and trivially enumerated, and as these are GET actions no CSRF token is involved.

The behavior's AJAX handlers (create_onSave, update_onSave, update_onDelete) were also dispatchable on these routes, but cross-user writes were blocked by the Backend\Models\User authorization guards added in v1.2.13. The confirmed impact is unauthorized disclosure of backend user profile data.

To actively exploit this security issue, an attacker would need access to the Backend with a user account with any level of access.

Patches

MyAccount no longer exposes the generic record actions it never used as routes, and its form lookup is now pinned to the authenticated user:

  • protected $guarded = ['create', 'update', 'preview']; removes the inherited actions from routing. The guard has to be at the routing layer, as handler dispatch ({action}_{handler}) runs before the page action.
  • formExtendQuery() constrains every lookup made by the behavior to the current user's key.

This security issue has been fixed as of v1.2.14 (commit cdbc8f5a23db27f72ccec658a8e5769e6d9f6dcb).

Workarounds

There is no supported workaround other than upgrading. If you cannot upgrade immediately, you may apply the fix manually in modules/backend/controllers/MyAccount.php:

  1. Add protected $guarded = ['create', 'update', 'preview']; to the controller.
  2. Add a formExtendQuery() method that scopes the lookup to the current user:
public function formExtendQuery(\Winter\Storm\Database\Builder $query): void
{
    $query->whereKey($this->user->getKey());
}

References

Credit to Awwader (@NRAwwad) for reporting the issue.

For more information

If you have any questions or comments about this advisory:

References

@LukeTowers LukeTowers published to wintercms/winter Aug 19, 2026
Published to the GitHub Advisory Database Aug 20, 2026
Reviewed Aug 20, 2026
Last updated Aug 20, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

EPSS score

Weaknesses

Authorization Bypass Through User-Controlled Key

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. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-mpmw-f6h6-3g26

Source code

Credits

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