CVE-2020-13666 — drupal/core
MEDIUMCVE-2020-13666 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in drupal/core. A fix is available for drupal/core — see the affected versions and patch details below.
Drupal Core Cross-site scripting vulnerability
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-2020-13666 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 376,715 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
drupal/core🐘drupal/core🐘drupal/core🐘drupal/core🐘drupal/drupal🐘drupal/drupal🐘drupal/drupal🐘drupal/drupalReal-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
Cross-site scripting vulnerability in Drupal Core. Drupal AJAX API does not disable JSONP by default, allowing for an XSS attack. This issue affects: Drupal Drupal Core 7.x versions prior to 7.73; 8.8.x versions prior to 8.8.10; 8.9.x versions prior to 8.9.6; 9.0.x versions prior to 9.0.6.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | drupal/core | ≥ 8.8.0&&< 8.8.10 | 8.8.10composer require drupal/core:^8.8.10 |
| 🐘Packagist | drupal/core | ≥ 8.9.0&&< 8.9.6 | 8.9.6composer require drupal/core:^8.9.6 |
| 🐘Packagist | drupal/core | ≥ 9.0.0&&< 9.0.6 | 9.0.6composer require drupal/core:^9.0.6 |
| 🐘Packagist | drupal/core | ≥ 7.0.0&&< 7.73 | 7.73composer require drupal/core:^7.73 |
| 🐘Packagist | drupal/drupal | ≥ 7.0.0&&< 7.73 | 7.73composer require drupal/drupal:^7.73 |
| 🐘Packagist | drupal/drupal | ≥ 8.8.0&&< 8.8.10 | 8.8.10composer require drupal/drupal:^8.8.10 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for drupal/core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update drupal/core to 8.8.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-13666 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-2020-13666 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2020-13666. 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-2020-13666 in your dependencies?
O3 Security finds CVE-2020-13666 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.