Vulnerability-Lookup

CVE-2026-54256 (GCVE-0-2026-54256)

Vulnerability from cvelistv5 – Published: 2026-08-26 17:53 – Updated: 2026-08-27 14:33

Title

Winter: Authenticated IDOR in backend FileUpload widget allows cross-user access to attachment metadata

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 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.

Severity

5.4 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-27 13:53 UTC

CWE

CWE-284 - Improper Access Control
CWE-639 - Authorization Bypass Through User-Controlled Key

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/wintercms/winter/security/advi…	x_refsource_CONFIRM
https://github.com/wintercms/winter/commit/9cb0ae…	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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                "id": "CVE-2026-54256",
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FKIE_CVE-2026-54256

Vulnerability from fkie_nvd - Published: 2026-08-26 18:16 - Updated: 2026-08-27 17:18

Severity

5.4 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/wintercms/winter/commit/9cb0ae5f9d837db141ab111c6a7de8eed9603d25
	security-advisories@github.com	https://github.com/wintercms/winter/security/advisories/GHSA-3277-h8g9-qj5f

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "winter",
          "vendor": "wintercms",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.2.13"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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\u0027s getFileRecord() lookup resolved the posted id against the global system_files table without verifying that the file belonged to the widget\u0027s 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."
    }
  ],
  "id": "CVE-2026-54256",
  "lastModified": "2026-08-27T17:18:47.507",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.4,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 2.5,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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          "options": [
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            }
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          "role": "CISA Coordinator",
          "timestamp": "2026-08-27T13:53:06.730759Z",
          "version": "2.0.3"
        }
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    ]
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  "published": "2026-08-26T18:16:40.780",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/wintercms/winter/commit/9cb0ae5f9d837db141ab111c6a7de8eed9603d25"
    },
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        }
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    }
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}

GHSA-3277-H8G9-QJ5F

Vulnerability from github – Published: 2026-08-20 18:39 – Updated: 2026-08-20 18:39

Summary

Winter: Authenticated IDOR in backend FileUpload widget allows cross-user access to attachment metadata

Details

Impact

The backend FileUpload form widget trusted an attacker-controlled file_id POST parameter when resolving the attachment it operates on. The lookup (FileUpload::getFileRecord()) 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.

Any authenticated backend user who can reach a form containing a fileupload field — including the built-in My Account avatar field, which requires no specific backend permission — could therefore target a System\Models\File record belonging to another user or record and:

modify its title and description via onSaveAttachmentConfig, and
change its sort_order via onSortAttachments (which passed posted ids straight to setSortableOrder(), an unscoped UPDATE ... WHERE id = ?).

The same unscoped lookup is reached by onLoadAttachmentConfig, onSaveAttachmentConfig, and onRemoveAttachment. Because all attachments share the single System\Models\File model and system_files table, an attacker was not limited to other users' avatars — any attachment on any model could be referenced by id. Attachment ids are sequential integers and are easily enumerated.

The confirmed impact is unauthorized integrity modification of arbitrary attachment metadata and ordering.

CSRF tokens are still verified on all POST requests, so an attacker must be authenticated to the backend with a valid session. To exploit this issue an attacker needs a backend account with any level of access.

Patches

The FileUpload widget now scopes every file_id lookup to the widget's own relation, including any files bound through the current deferred-binding session, so a posted id can no longer reference an unrelated System\Models\File record:

getFileRecord() resolves the id through getRelationObject()->withDeferred($this->sessionKey)->find(...) rather than the global file model. This covers onLoadAttachmentConfig, onSaveAttachmentConfig, and onRemoveAttachment.
onSortAttachments() intersects the posted ids with the ids that actually belong to the relation before calling setSortableOrder().

This security issue has been fixed as of v1.2.13 (commit 9cb0ae5f9d837db141ab111c6a7de8eed9603d25).

Workarounds

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

In getFileRecord(), replace $this->getRelationModel()->find(post('file_id')) with $this->getRelationObject()->withDeferred($this->sessionKey)->find(post('file_id')).
In onSortAttachments(), filter the posted sortOrder ids to those returned by $this->getRelationObject()->withDeferred($this->sessionKey)->pluck($keyName) before calling setSortableOrder().

Severity

5.4 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Show details on source website

JSON

To clipboard

{
  "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-2026-54256"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-284",
      "CWE-639"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-20T18:39:56Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nThe backend `FileUpload` form widget trusted an attacker-controlled `file_id` POST parameter when resolving the attachment it operates on. The lookup (`FileUpload::getFileRecord()`) resolved the posted id against the global `system_files` table without verifying that the file belonged to the widget\u0027s own relation, parent record, or deferred-binding session.\n\nAny authenticated backend user who can reach a form containing a `fileupload` field \u2014 including the built-in **My Account** avatar field, which requires no specific backend permission \u2014 could therefore target a `System\\Models\\File` record belonging to another user or record and:\n\n- modify its `title` and `description` via `onSaveAttachmentConfig`, and\n- change its `sort_order` via `onSortAttachments` (which passed posted ids\n  straight to `setSortableOrder()`, an unscoped `UPDATE ... WHERE id = ?`).\n\nThe same unscoped lookup is reached by `onLoadAttachmentConfig`, `onSaveAttachmentConfig`, and `onRemoveAttachment`. Because all attachments share the single `System\\Models\\File` model and `system_files` table, an attacker was not limited to other users\u0027 avatars \u2014 any attachment on any model could be referenced by id. Attachment ids are sequential integers and are easily enumerated.\n\nThe confirmed impact is unauthorized integrity modification of arbitrary attachment metadata and ordering.\n\nCSRF tokens are still verified on all POST requests, so an attacker must be authenticated to the backend with a valid session. To exploit this issue an attacker needs a backend account with any level of access.\n\n### Patches\n\nThe `FileUpload` widget now scopes every `file_id` lookup to the widget\u0027s own relation, including any files bound through the current deferred-binding session, so a posted id can no longer reference an unrelated `System\\Models\\File` record:\n\n- `getFileRecord()` resolves the id through `getRelationObject()-\u003ewithDeferred($this-\u003esessionKey)-\u003efind(...)` rather than the global file model. This covers `onLoadAttachmentConfig`, `onSaveAttachmentConfig`, and `onRemoveAttachment`.\n- `onSortAttachments()` intersects the posted ids with the ids that actually belong to the relation before calling `setSortableOrder()`.\n\nThis security issue has been fixed as of **v1.2.13** (commit [`9cb0ae5f9d837db141ab111c6a7de8eed9603d25`](https://github.com/wintercms/winter/commit/9cb0ae5f9d837db141ab111c6a7de8eed9603d25)).\n\n### Workarounds\n\nThere is no supported workaround other than upgrading. If you cannot upgrade immediately, you may apply the fix manually in `modules/backend/formwidgets/FileUpload.php`:\n\n1. In `getFileRecord()`, replace `$this-\u003egetRelationModel()-\u003efind(post(\u0027file_id\u0027))` with `$this-\u003egetRelationObject()-\u003ewithDeferred($this-\u003esessionKey)-\u003efind(post(\u0027file_id\u0027))`.\n2. In `onSortAttachments()`, filter the posted `sortOrder` ids to those returned by `$this-\u003egetRelationObject()-\u003ewithDeferred($this-\u003esessionKey)-\u003epluck($keyName)` before calling `setSortableOrder()`.",
  "id": "GHSA-3277-h8g9-qj5f",
  "modified": "2026-08-20T18:39:56Z",
  "published": "2026-08-20T18:39:56Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/wintercms/winter/security/advisories/GHSA-3277-h8g9-qj5f"
    },
    {
      "type": "WEB",
      "url": "https://github.com/wintercms/winter/security/advisories/GHSA-qq9m-vfv4-pj5w"
    },
    {
      "type": "WEB",
      "url": "https://github.com/wintercms/winter/commit/9cb0ae5f9d837db141ab111c6a7de8eed9603d25"
    },
    {
      "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:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Winter: Authenticated IDOR in backend FileUpload widget allows cross-user access to attachment metadata"
}

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.

Action not permitted

CVE-2026-54256 (GCVE-0-2026-54256)

FKIE_CVE-2026-54256

GHSA-3277-H8G9-QJ5F

Impact

Patches

Workarounds

Tags

Sightings

Nomenclature