CVE-2011-2509 — joomla/joomla-cms
CVE-2011-2509 is a Cross-site Scripting (XSS) vulnerability in joomla/joomla-cms. 2 public exploit references exist, so weaponization risk is real. A fix is available for joomla/joomla-cms — see the affected versions and patch details below.
Joomla! vulnerable to Cross-site Scripting
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.
Real-World Exposure
joomla/joomla-cmsReal-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
Multiple cross-site scripting (XSS) vulnerabilities in Joomla! before 1.6.4 allow remote attackers to inject arbitrary web script or HTML via (1) the query string to the com_contact component, as demonstrated by the Itemid parameter to index.php; (2) the query string to the com_content component, as demonstrated by the filter_order parameter to index.php; (3) the query string to the com_newsfeeds component, as demonstrated by an arbitrary parameter to index.php; or (4) the option parameter in a reset.request action to index.php; and, when Internet Explorer or Konqueror is used, (5) allow remote attackers to inject arbitrary web script or HTML via the searchword parameter in a search action to index.php in the com_search component.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | joomla/joomla-cms | all versions | 1.6.4composer require joomla/joomla-cms:^1.6.4 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for joomla/joomla-cms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update joomla/joomla-cms to 1.6.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2011-2509 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-2011-2509 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2011-2509. 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-2011-2509 in your dependencies?
O3 Security finds CVE-2011-2509 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.