# CVE-2026-125338: Winter CMS: Stored XSS through cached Brand Settings and Editor Settings custom styles

Status: published. Published: 2026-11-10. Updated: 2026-11-14.

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.

## Remediation

- fix: winter/wn-backend-module (Packagist): OSV reports a fixed version 1.2.14. Check the advisory for supported release branches. (source: OSV GHSA-5cwr-5jxg-pcf6) — https://github.com/advisories/GHSA-5cwr-5jxg-pcf6

## Affected products and versions

- wintercms / winter: < 1.2.14 (affected). Source: CNA: GitHub_M
-  / winter/wn-backend-module (winter/wn-backend-module): v1.0.473 (affected, Packagist); v1.0.474 (affected, Packagist); v1.0.475 (affected, Packagist); v1.1.10 (affected, Packagist); v1.1.11 (affected, Packagist); v1.1.2 (affected, Packagist); v1.1.3 (affected, Packagist); v1.1.4 (affected, Packagist); v1.1.5 (affected, Packagist); v1.1.6 (affected, Packagist); v1.1.7 (affected, Packagist); v1.1.8 (affected, Packagist); v1.1.9 (affected, Packagist); v1.2.0 (affected, Packagist); v1.2.1 (affected, Packagist); v1.2.10 (affected, Packagist); v1.2.11 (affected, Packagist); v1.2.12 (affected, Packagist); v1.2.13 (affected, Packagist); v1.2.2 (affected, Packagist); v1.2.3 (affected, Packagist); v1.2.4 (affected, Packagist); v1.2.5 (affected, Packagist); v1.2.6 (affected, Packagist); v1.2.7 (affected, Packagist); v1.2.8 (affected, Packagist); v1.2.9 (affected, Packagist); Ecosystem version events: introduced 0; fixed 1.2.14. Source: OSV GHSA-5cwr-5jxg-pcf6

## Severity and prioritization

- CVSS 3.1: 4.5 (medium); CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:H/A:N; source: CNA: GitHub_M

- CVSS 3.1: 4.5 (medium); CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:H/A:N; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: 0.40% as of 2026-11-13; percentile 34.24%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-79

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/wintercms/winter/security/advisories/GHSA-5cwr-5jxg-pcf6 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/wintercms/winter/commit/c95d780ab54f3a3f74a94ae1667bf12b3c549d5d (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/wintercms/winter/releases/tag/v1.2.14 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/wintercms/winter/commit/c95d780ab54f3a3f74a94ae1667bf12b3c549d5d (security-advisories@github.com)

- https://github.com/wintercms/winter/releases/tag/v1.2.14 (security-advisories@github.com)

- https://github.com/wintercms/winter/security/advisories/GHSA-5cwr-5jxg-pcf6 (security-advisories@github.com)

- https://github.com/advisories/GHSA-5cwr-5jxg-pcf6 (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-5cwr-5jxg-pcf6 (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-125338; retrieved 2026-11-14; source updated 2026-11-14

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-125338; retrieved 2026-11-13; source updated 2026-11-12

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-5cwr-5jxg-pcf6; retrieved 2026-11-10; source updated 2026-11-10

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-125338; retrieved 2026-11-14; source updated Not reported

Revision: 5b9ba1b0140f19cc502d36cfd5a6c753641a5a2b844ba25be9e140dfeb55a90f

Canonical: https://y2.dev/cve/CVE-2026-125338

## Agent and API access

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- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

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