Winter CMS up to 1.2.13 Backend Style Rendering renderCss cross site scripting

Summaryinfo

A vulnerability marked as problematic has been reported in Winter CMS up to 1.2.13. Affected is the function BrandSetting::renderCss/EditorSetting::renderCss of the component Backend Style Rendering. Performing a manipulation results in cross site scripting. This vulnerability is reported as CVE-2026-125338. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Winter CMS up to 1.2.13. It has been classified as problematic. This affects the function BrandSetting::renderCss/EditorSetting::renderCss of the component Backend Style Rendering. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. The summary by CVE is:

Winter CMS is a content management system built on the Laravel PHP framework. Prior to 1.2.14, BrandSetting::renderCss() and EditorSetting::renderCss() store raw LESS compiler output with Cache::forever() but apply strip_tags() only to the value returned on a cache miss. The first render after saving custom CSS appears sanitized while priming an unsafe cache entry, and later cache hits return unsanitized output into the backend style element, allowing a user with backend.manage_branding or backend.manage_editor to cause stored cross-site scripting when another backend page renders the styles. The styles also appear on unauthenticated backend sign-in, password restore, and password reset layouts. This issue is fixed in version 1.2.14.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-125338 since 11/09/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Additional levels of successful authentication are required for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 1.2.14 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Content Management System

Name

• Winter CMS

Version

• 1.2.0
• 1.2.1
• 1.2.2
• 1.2.3
• 1.2.4
• 1.2.5
• 1.2.6
• 1.2.7
• 1.2.8
• 1.2.9
• 1.2.10
• 1.2.11
• 1.2.12
• 1.2.13

CPE 2.3info

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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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