CVE-2025-61676 — october/system
MEDIUMCVE-2025-61676 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in october/system. A fix is available for october/system — see the affected versions and patch details below.
October CMS Vulnerable to Stored XSS via Branding Styles
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-61676.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2025-61676 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
october/system🐘october/systemReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | october/system | all versions | 3.7.13composer require october/system:^3.7.13 |
| 🐘Packagist | october/system | ≥ 4.0.0&&< 4.0.12 | 4.0.12composer require october/system:^4.0.12 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for october/system, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update october/system to 3.7.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-61676 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-61676 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-61676. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-61676 in your dependencies?
O3 Security finds CVE-2025-61676 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.