How severe is CVE-2013-4939?

No CVSS score has been assigned to CVE-2013-4939 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2013-4939?

CVE-2013-4939 affects the following packages: yui (npm). Ecosystems affected: npm.

How do I fix CVE-2013-4939?

Update yui to 3.10.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2013-4939 is resolved across your whole dependency graph.

How do I detect CVE-2013-4939 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yui. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2013-4939 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2013-4939?

O3 pinpoints whether CVE-2013-4939 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2013-4939 actively exploited in the wild?

No public exploit code has been indexed for CVE-2013-4939 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 type of vulnerability is CVE-2013-4939?

CVE-2013-4939 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-2013-4939 published, and has it been updated?

CVE-2013-4939 was published on September 1, 2020 and was last updated on November 8, 2023. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

CVE-2013-4939

CVE-2013-4939 is a Cross-site Scripting (XSS) vulnerability in yui. O3 Security confirms whether CVE-2013-4939 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Cross-Site Scripting in yui

Published

Sep 1, 2020

Updated

Nov 8, 2023

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 8, 2023 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

📦yui

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Affected versions of yui are vulnerable to cross-site scripting in the uploader.swf and io.swf utilities, via script injection in the url.

Recommendation

YUI has published their recommendation to fix this issue. Their recommendation is to:

Delete self-hosted copies of these files if you are not using them
Use the Yahoo! CDN hosted files
Use the patched files provided on the YUI Library here.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`yui`	all versions	3.10.3

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yui. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update yui to 3.10.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2013-4939 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 pinpoints whether CVE-2013-4939 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2013-4939. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Affected versions of `yui` are vulnerable to cross-site scripting in the `uploader.swf` and `io.swf` utilities, via script injection in the url. ## Recommendation YUI has published their recommendation to fix this issue. Their recommendation is to: - Delete self-hosted copies of these files if you are not using them - Use the Yahoo! CDN hosted files - Use the patched files provided on the YUI Library [here](https://yuilibrary.com/support/20130515-vulnerability/#resolution).

O3 Security · Impact-Aware SCA

Is CVE-2013-4939 in your dependencies?

O3 detects CVE-2013-4939 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works