Unrated

Broken access control in Winter CMS Theme Editor

IdentifiersCVE-2026-32639CWE-284

CVE-2026-32639 is a broken access control vulnerability in the Winter CMS backend Theme Editor, specifically in Cms\Controllers\Index. The flaw allows a backend user who holds any single Theme Editor-related permission to bypass intended granular authorization boundaries between template types. As a result, AJAX handlers associated with template operations do not consistently enforce per-template-type permission checks, enabling cross-template actions outside the user’s assigned scope. The issue also affects asset handling by allowing unauthorized file uploads into the active theme asset directory when asset-related access validation is insufficient.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an authenticated backend user to read, modify, or delete theme templates beyond the scope intended by their assigned permissions. The vulnerability also permits unauthorized uploads into the active theme asset directory. This can lead to unauthorized content changes, defacement, integrity loss of site themes and templates, and potentially creation of a foothold for further abuse depending on how uploaded assets are processed or served within the application.

Mitigation

If you can’t patch tonight, do this now.

If an upgrade cannot be applied immediately, manually harden the affected code by adding explicit permission checks around each Theme Editor widget registration, enforcing request-type validation on template-related AJAX handlers including open, save, create, delete, commit, and reset operations, and adding theme validation at the start of the asset upload handler. As an operational mitigation, restrict backend access to trusted administrators only and remove unnecessary Theme Editor permissions until the fix is deployed.

Remediation

Patch, then assume compromise.

Upgrade Winter CMS to version 1.2.13 or later. The fixed release enforces per-template-type permission checks on Theme Editor AJAX handlers, restricts AssetList registration to users with the asset-management permission, and adds theme validation to the upload handler.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

ACTIVITY FEED

Recent activity

No public activity tracked yet. Mallory keeps watching.

0 SOURCESView more in app

No public activity observed for this vulnerability.

What this page doesn’t show

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity