How severe is CVE-2011-2509?

No CVSS score has been assigned to CVE-2011-2509 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2011-2509?

CVE-2011-2509 affects the following packages: joomla/joomla-cms (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2011-2509?

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.

How do I detect CVE-2011-2509 in my Packagist dependencies?

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.

How do I mitigate CVE-2011-2509 if there is no patch (or I can't update yet)?

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.

Is CVE-2011-2509 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2011-2509, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2011-2509?

CVE-2011-2509 has an EPSS (Exploit Prediction Scoring System) score of 1.1%, placing it in the 65th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2011-2509?

CVE-2011-2509 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2011-2509 published, and has it been updated?

CVE-2011-2509 was published on May 14, 2022 and was last updated on April 12, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

CVE-2011-2509 — joomla-cms

CVE-2011-2509 is a Cross-site Scripting (XSS) vulnerability in joomla/joomla-cms. 2 public exploit or proof-of-concept references are indexed, 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

Published

May 14, 2022

Updated

Apr 12, 2025

Affected

1 pkg

Patched

1 / 1

Exploits

2 known

Exploitation data as of Oct 28, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs65th percentile — riskier than 65% of all scored CVEsHighest risk

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

Real-World Exposure

1 pkg affected

🐘joomla/joomla-cms

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

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

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`joomla/joomla-cms`	all versions	1.6.4`composer require joomla/joomla-cms:^1.6.4`

Affected Products

1 product · 46 configurations

Application

joomla\!joomla

≤ 1.6.3

27 versions

1.5.01.5.11.5.21.5.31.5.41.5.51.5.61.5.71.5.81.5.91.5.101.5.11

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Multiple cross-site scripting (XSS) vulnerabilities in Joomla! before 1.…

openwall.comNVDAug 2018

Report on openwall.com

openwall.comNVDAug 2018

Detection & mitigation playbook

Open-source dependency

Detect
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
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

O3 Security · Impact-Aware SCA

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