CVE-2026-27937 — october/system
LOWCVE-2026-27937 is a low-severity (CVSS 3.1) 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: Reflected XSS via DataTable Form Widget
Exploitation Status
No confirmed exploitation observed yet
- 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-2026-27937.
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-2026-27937 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 reflected Cross-Site Scripting (XSS) vulnerability was identified in the backend DataTable widget where a query parameter was rendered without proper output escaping.
Impact
- Reflected XSS only, no stored/persistent component
- The backend URL prefix is customizable and must be known or guessed by the attacker
- Requires an authenticated backend user to visit a crafted URL
- No direct access is gained without social engineering
Patches
The vulnerability has been patched in v3.7.16 and v4.1.16. The affected parameter is now properly escaped. All users are encouraged to upgrade to the latest patched version.
Workarounds
- Use a non-default backend URL prefix (recommended as standard practice)
- Implement a Content Security Policy (CSP) for backend pages
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | october/system | all versions | 3.7.16composer require october/system:^3.7.16 |
| 🐘Packagist | october/system | ≥ 4.0.0 | No fix |
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 3.7.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-27937 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-2026-27937 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-27937. 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-2026-27937 in your dependencies?
O3 Security finds CVE-2026-27937 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.