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CVE-2026-54256 medium CVSS 5.4

Vulnerability in winter/wn-backend-module (CVE-2026-54256)

Summary

Vulnerability in winter/wn-backend-module (CVE-2026-54256). Risk of unauthorized operations or information disclosure. Exploitable via FileUpload. Mitigation: upgrade to 1.2.13 or later.

Original description

The description as published by the source.

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.…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-54256 has been found in winter/wn-backend-module.
Attackers can target a specific entry point like FileUpload over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: upgrade winter/wn-backend-module to 1.2.13 or later.
If unsure, ask your IT team or search "winter/wn-backend-module CVE-2026-54256" on the vendor's site.

CVE-2026-54256 (winter/wn-backend-module) — CWE-284 / CVSS v3 5.4
Attack vector: remote (network-reachable) / no user interaction
Attack surface: FileUpload / file_id / system_files / fileupload
Patched: 1.2.13 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-284) exists in winter/wn-backend-module. Attackers reach the vulnerable code path via FileUpload.

📍 Affected scope

Check the vendor advisory for the affected versions of winter/wn-backend-module. Attack surface: FileUpload / file_id / system_files / fileupload.

🔥 Severity

Severity: Medium (CVSS 5.4/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 1.2.13.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'winter/wn-backend-module' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'winter/wn-backend-module' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で winter/wn-backend-module を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade winter/wn-backend-module to 1.2.13

    ステージング環境で 1.2.13 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

composer winter/wn-backend-module
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.13"}]}]
Packagist winter/wn-backend-module
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.13"}]}]

References

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