How severe is CVE-2013-4942?

No CVSS score has been assigned to CVE-2013-4942 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2013-4942?

CVE-2013-4942 affects the following packages: yui (npm), moodle/moodle (Packagist), moodle/moodle (Packagist), moodle/moodle (Packagist), moodle/moodle (Packagist). Ecosystems affected: npm, Packagist.

How do I fix CVE-2013-4942?

A fix is available for CVE-2013-4942; check the affected-versions list above or the advisory for the patched release of yui, then make sure no transitive dependency still pins the vulnerable range.

How do I detect CVE-2013-4942 in my npm, Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yui, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2013-4942 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-2013-4942 actively exploited in the wild?

No public exploit code has been indexed for CVE-2013-4942 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2013-4942?

CVE-2013-4942 has an EPSS (Exploit Prediction Scoring System) score of 1.2%, placing it in the 68th 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-2013-4942?

CVE-2013-4942 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-2013-4942 published, and has it been updated?

CVE-2013-4942 was published on May 13, 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.

CVE-2013-4942: yui XSS — Fixed in 2.2.11

EPSS Exploitation Probability

via FIRST.org ↗

1.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs68th percentile — riskier than 68% of all scored CVEsHighest risk

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

Real-World Exposure

5 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

53other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

yuinpm

31Kdownloads / week

Description

Cross-site scripting (XSS) vulnerability in flashuploader.swf in the Uploader component in Yahoo! YUI 3.5.0 through 3.9.1, as used in Moodle through 2.1.10, 2.2.x before 2.2.11, 2.3.x before 2.3.8, 2.4.x before 2.4.5, 2.5.x before 2.5.1, and other products, allows remote attackers to inject arbitrary web script or HTML via a crafted string in a URL.

Affected Packages

5 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`yui`	≥ 3.2.0	No fix
🐘Packagist	`moodle/moodle`	all versions	2.2.11`composer require moodle/moodle:^2.2.11`
🐘Packagist	`moodle/moodle`	≥ 2.3.0&&< 2.3.8	2.3.8`composer require moodle/moodle:^2.3.8`
🐘Packagist	`moodle/moodle`	≥ 2.4.0-rc1&&< 2.4.5	2.4.5`composer require moodle/moodle:^2.4.5`
🐘Packagist	`moodle/moodle`	≥ 2.5.0-beta&&< 2.5.1	2.5.1`composer require moodle/moodle:^2.5.1`

Affected Products

2 products · 50 configurations

Application

moodlemoodle

36 versions

2.1.02.1.12.1.22.1.32.1.42.1.52.1.62.1.72.1.82.1.92.1.102.2.0

Application

yuiyahoo

14 versions

3.5.03.5.13.6.03.7.03.7.13.7.23.7.33.8.03.8.13.9.03.9.13.10.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yui, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
A fix is available for CVE-2013-4942; check the affected-versions list above or the advisory for the patched release of yui, then make sure no transitive dependency still pins the vulnerable range.
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

Cross-site scripting (XSS) vulnerability in flashuploader.swf in the Uploader component in Yahoo! YUI 3.5.0 through 3.9.1, as used in Moodle through 2.1.10, 2.2.x before 2.2.11, 2.3.x before 2.3.8, 2.4.x before 2.4.5, 2.5.x before 2.5.1, and other products, allows remote attackers to inject arbitrary web script or HTML via a crafted string in a URL.

O3 Security · Impact-Aware SCA

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CVE-2013-4942 — yui