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Not in CISA KEV
LOW severity

CVE-2026-27937 — system

LOW

CVE-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

Published
Updated
Affected
2 pkgs
Patched
1 / 2
Exploits
None indexed
Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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

via FIRST.org ↗
0.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs4th percentile — riskier than 4% of all scored CVEsHighest risk
0.00%0.24%0.49%0.73%0.0%0.1%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected
🐘october/system🐘october/system

Real-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

2 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistoctober/systemall versions3.7.16composer require october/system:^3.7.16
🐘Packagistoctober/system≥ 4.0.0No fix

Detection & mitigation playbook

Open-source dependency

  1. Detect

    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.

  2. 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.

  3. Workarounds

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

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 t
O3 Security · Impact-Aware SCA

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CVE-2026-27937: system XSS — Fixed in 3.7.16