Vulnerability · Published Aug 26, 2026 · Assigned by GitHub_M

CVE-2026-32257Winter: Stored XSS through Brand Settings custom styles

High 8.1

In plain English

A high-severity cross-site scripting in winter from wintercms. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.1High

Exploit odds (30 days)0.4%top 67.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Winter is a free, open-source content management system (CMS) based on the Laravel PHP framework. Prior to 1.2.13, custom CSS supplied through the Brand Settings Styles field by a backend user with the backend.manage_branding permission is compiled by the LESS parser and rendered without sanitization on every backend page, allowing stored cross-site scripting against backend users. This issue is fixed in version 1.2.13.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Packagist	winter/wn-backend-module	1.2.13	GHSA-v7cf-8gh9-gxmj

Affected products (as reported)

Vendor	Product	Versions
wintercms	winter	< 1.2.13

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N

References

https://github.com/wintercms/winter/security/advisories/GHSA-v7cf-8gh9-gxmj x_refsource_CONFIRM
https://github.com/wintercms/winter/commit/d28f0b9474af79cfaa80eeb9d691f7a7c4469720 x_refsource_MISC