# CVE-2026-125338: Winter CMS stored XSS in backend brand and editor settings

Source: https://junglewise.ai/threats/cve-2026-125338-winter-cms-is-a-content-management-system-built-on-the-laravel  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-125338 · Severity: medium · CVSS 4.5 · Published 2026-11-10

Winter CMS is a content management system built on Laravel. Users with branding or editor management permissions can inject malicious CSS that bypasses sanitization due to a caching issue, causing stored cross-site scripting attacks when other backend users view the styles. The injected styles also appear on unauthenticated login and password reset pages, potentially compromising accounts.

Technologies: [Winter CMS](https://junglewise.ai/threats/technologies/winter-cms). Vendors: [Winter CMS](https://junglewise.ai/threats/vendors/winter-cms).

## Quick answers

**Is CVE-2026-125338 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-125338 being exploited in the wild.

**How severe is CVE-2026-125338?** Medium severity, with a CVSS score of 4.5, published 10 November 2026.

**Which products and versions are affected?** Winter CMS prior to 1.2.14.

**Is there a fix for CVE-2026-125338?** Yes: fixed in 1.2.14. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-125338 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-125338?** Check whether you run Winter CMS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 1.2.14

## Technical details

The BrandSetting::renderCss() and EditorSetting::renderCss() methods cache LESS compiler output indefinitely using Cache::forever() but only sanitize the output on cache misses. An attacker with backend.manage_branding or backend.manage_editor permissions can craft malicious LESS that appears sanitized on first render while poisoning the cache with unsanitized output, which is then served to all subsequent users. This stored XSS affects authenticated backend users and extends to unauthenticated pages (sign-in, password reset).

## Affected products

- Winter CMS Winter CMS prior to 1.2.14

## Timeline

- 2026-11-10: disclosed

## References

- [https://github.com/wintercms/winter/commit/c95d780ab54f3a3f74a94ae1667bf12b3c549d5d](https://github.com/wintercms/winter/commit/c95d780ab54f3a3f74a94ae1667bf12b3c549d5d)
- [https://github.com/wintercms/winter/releases/tag/v1.2.14](https://github.com/wintercms/winter/releases/tag/v1.2.14)

## Related threats

- [Winter CMS MyAccount controller information disclosure](https://junglewise.ai/threats/cve-2026-126061-winter-cms-is-a-content-management-system-built-on-the-laravel)
- [Winter CMS reflected XSS in Table widget search parameter](https://junglewise.ai/threats/cve-2026-125340-winter-cms-is-a-content-management-system-built-on-the-laravel)
- [Winter CMS CSRF via unvalidated backend handler invocation](https://junglewise.ai/threats/cve-2026-125339-winter-cms-is-a-content-management-system-built-on-the-laravel)
- [Winter CMS local file inclusion via LESS @import directives](https://junglewise.ai/threats/cve-2026-63179-winter-cms-local-file-inclusion-via-less-import-directives)
- [Winter CMS broken access control in Cms Controllers Index](https://junglewise.ai/threats/cve-2026-32639-winter-cms-broken-access-control-in-cms-controllers-index)