October CMS Vulnerable to Stored XSS via Branding Styles
A cross-site scripting (XSS) vulnerabilities was identified in October CMS backend configuration forms:
- Branding and Appearances Styles
A user with theCustomize Backend Stylespermission could inject malicious HTML/JS into the stylesheet input at
Settings → Branding & Appearance → Styles.
A specially crafted input could break out of the intended <style> context, allowing arbitrary script execution across backend pages for all users.
Impact
- Persistent XSS across the backend interface.
- Exploitable by lower-privileged accounts with the above permissions.
- Potential consequences include privilege escalation, session hijacking, and execution of unauthorized actions in victim sessions.
Patches
The vulnerability has been patched in v4.0.12 and v3.7.13.
Stylesheet inputs are now sanitized to prevent injection of arbitrary HTML/JS.
All users are strongly encouraged to upgrade to the latest patched version.
Workarounds
If upgrading immediately is not possible:
- Restrict the permissions
Customize Backend Stylesto fully trusted administrators only.
This reduces exposure but does not fully eliminate risk.
Credits
- Reported by Nakkouch Tarek
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Paquete de Composer | october/system | < 3.7.13, >= 4.0.0, < 4.0.12 | 3.7.13, 4.0.12 |
Referencias
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N- Debilidad (CWE)
CWE-79- Plataforma
- Composer
- Paquete
october/system- Publicada
- 09.01.2026
- Actualizado
- 11.10.2026 10:22
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-wvpq-h33f-8rp6 - CC BY 4.0
Historial de vulnerabilidades: october/system
Todas las vulnerabilidades publicadas de este paquete (Paquete de Composer), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 25
- Primera → última
- 06.2020 09.2026
- Sin corrección
- 0
- Explotada en ataques
- 1
Distribución por gravedad
- Crítica 1
- Alta 8
- Media 9
- Baja 7
Divulgaciones por año
- 2020: 1
- 2021: 3
- 2022: 6
- 2023: 3
- 2024: 2
- 2025: 1
- 2026: 9
-
October CMS Vulnerable to Stored XSS via Branding Styles esta entrada
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