Vulnerability-Lookup

CVE-2026-35445 (GCVE-0-2026-35445)

Vulnerability from cvelistv5 – Published: 2026-08-26 16:40 – Updated: 2026-08-26 19:08

Title

Winter: Authenticated backend users can bypass Users controller permission checks

Summary

Winter CMS is a content management system built on the Laravel PHP framework. In versions prior to 1.2.13, the backend did not validate the handler name submitted through the form postback _handler POST field, allowing an authenticated backend user to invoke arbitrary controller methods, including protected, private, and action-prefixed ones. While AJAX requests validate that handler names match the on[A-Z][\w+]* pattern, the postback path passed the submitted _handler value straight to the handler dispatcher with no such check, so any controller that exposes a public action or conditionally relaxes its $requiredPermissions check could be reached, bypassing the roles and permissions system. The built-in Users controller was affected because it set $requiredPermissions to null for the myaccount action, letting any authenticated backend user invoke user-management methods such as update_onDelete and update_onManualPasswordReset without holding the backend.manage_users permission. This issue is fixed in version 1.2.13.

Severity

7.1 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-26 19:07 UTC

CWE

CWE-285 - Improper Authorization

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/wintercms/winter/security/advi…	x_refsource_CONFIRM
https://github.com/wintercms/winter/pull/1473	x_refsource_MISC
https://github.com/wintercms/winter/releases/tag/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
wintercms	winter	Affected: < 1.2.13	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-35445

Vulnerability from fkie_nvd - Published: 2026-08-26 17:16 - Updated: 2026-09-09 21:09

Severity

7.1 (High) - CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/wintercms/winter/pull/1473
	security-advisories@github.com	https://github.com/wintercms/winter/releases/tag/v1.2.13
	security-advisories@github.com	https://github.com/wintercms/winter/security/advisories/GHSA-j5jq-cr68-v2xx

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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GHSA-J5JQ-CR68-V2XX

Vulnerability from github – Published: 2026-08-12 15:15 – Updated: 2026-08-12 15:15

Summary

Winter: Authenticated backend users can bypass Users controller permission checks

Details

Impact

Affected versions of Winter CMS did not validate the handler name submitted through the form postback mechanism (_handler POST field) in the same way as AJAX requests (X_WINTER_REQUEST_HANDLER header). The AJAX path validates that handler names match the on[A-Z][\w+]* pattern, but the postback path passed the handler name directly to the handler dispatcher with no validation.

This allowed an authenticated backend user to call any method on a controller — including action-prefixed, protected, and private methods — by submitting a crafted POST request with a _handler field, as long as the controller either:

Contains a publicly available action via the $publicActions property, or
Degrades or removes the $requiredPermissions check in its constructor based on a condition

The backend's own Users controller was affected by the second scenario: it set $requiredPermissions to null for the myaccount action, allowing any authenticated backend user to access the controller without the backend.manage_users permission. Combined with the postback bypass, this allowed calling controller methods such as update_onDelete, update_onRestore, update_onUnsuspendUser, and update_onManualPasswordReset with attacker-controlled parameters.

Note that CSRF tokens are still verified on all POST requests, so the attacker must be logged into the backend with a valid session.

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

The Winter CMS maintainers strongly recommend that all Winter CMS sites that have any reliance on the roles & permissions system to update immediately. Security fixes have been backported to all major versions of Winter (1.0, 1.1, and 1.2).

Patches

The postback handler path now validates handler names using the same rules as the AJAX path. The My Account functionality has been moved to a dedicated controller that does not expose user management methods. Defence in depth has been applied at the model level to prevent unauthorized user record modifications regardless of the entry point.

This security issue has been fixed as of v1.2.13.

Workarounds

If users cannot upgrade, they may apply the following changes to their Winter CMS installation manually to resolve this issue:

In modules/backend/classes/Controller.php, validate the _handler POST field against the on[A-Z][\w+]* pattern before passing it to runAjaxHandler().
In modules/backend/controllers/Users.php, remove the conditional that sets $requiredPermissions to null for the myaccount action.

Severity

7.1 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.2.12"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "winter/wn-backend-module"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.2.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-35445"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-285",
      "CWE-639"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-12T15:15:17Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Impact\n\nAffected versions of Winter CMS did not validate the handler name submitted through the form postback mechanism (`_handler` POST field) in the same way as AJAX requests (`X_WINTER_REQUEST_HANDLER` header). The AJAX path validates that handler names match the `on[A-Z][\\w+]*` pattern, but the postback path passed the handler name directly to the handler dispatcher with no validation.\n\nThis allowed an authenticated backend user to call any method on a controller \u2014 including action-prefixed, protected, and private methods \u2014 by submitting a crafted POST request with a `_handler` field, as long as the controller either:\n\n- Contains a publicly available action via the `$publicActions` property, or\n- Degrades or removes the `$requiredPermissions` check in its constructor based on a condition\n\nThe backend\u0027s own Users controller was affected by the second scenario: it set `$requiredPermissions` to `null` for the `myaccount` action, allowing any authenticated backend user to access the controller without the `backend.manage_users` permission. Combined with the postback bypass, this allowed calling controller methods such as `update_onDelete`, `update_onRestore`, `update_onUnsuspendUser`, and `update_onManualPasswordReset` with attacker-controlled parameters.\n\nNote that CSRF tokens are still verified on all POST requests, so the attacker must be logged into the backend with a valid session.\n\nTo actively exploit this security issue, an attacker would need access to the Backend with a user account with any level of access.\n\nThe Winter CMS maintainers strongly recommend that all Winter CMS sites that have any reliance on the roles \u0026 permissions system to update immediately. Security fixes have been backported to all major versions of Winter (1.0, 1.1, and 1.2).\n\n### Patches\n\nThe postback handler path now validates handler names using the same rules as the AJAX path. The My Account functionality has been moved to a dedicated controller that does not expose user management methods. Defence in depth has been applied at the model level to prevent unauthorized user record modifications regardless of the entry point.\n\nThis security issue has been fixed as of v1.2.13.\n\n### Workarounds\n\nIf users cannot upgrade, they may apply the following changes to their Winter CMS installation manually to resolve this issue:\n\n1. In `modules/backend/classes/Controller.php`, validate the `_handler` POST field against the `on[A-Z][\\w+]*` pattern before passing it to `runAjaxHandler()`.\n2. In `modules/backend/controllers/Users.php`, remove the conditional that sets `$requiredPermissions` to `null` for the `myaccount` action.",
  "id": "GHSA-j5jq-cr68-v2xx",
  "modified": "2026-08-12T15:15:17Z",
  "published": "2026-08-12T15:15:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/wintercms/winter/security/advisories/GHSA-j5jq-cr68-v2xx"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/wintercms/winter"
    },
    {
      "type": "WEB",
      "url": "https://github.com/wintercms/winter/releases/tag/v1.2.13"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Winter: Authenticated backend users can bypass Users controller permission checks"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-35445 (GCVE-0-2026-35445)

FKIE_CVE-2026-35445

GHSA-J5JQ-CR68-V2XX

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