How severe is CVE-2016-4567?

CVE-2016-4567 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2016-4567?

CVE-2016-4567 affects the following packages: mediaelement (npm), contao-components/mediaelement (Packagist), contao/core (Packagist). Ecosystems affected: npm, Packagist.

How do I fix CVE-2016-4567?

Update mediaelement to 2.11.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-4567 is resolved across your whole dependency graph.

How do I detect CVE-2016-4567 in my npm, Packagist dependencies?

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

How do I mitigate CVE-2016-4567 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-2016-4567 actively exploited in the wild?

No public exploit code has been indexed for CVE-2016-4567 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-2016-4567?

CVE-2016-4567 has an EPSS (Exploit Prediction Scoring System) score of 7.4%, placing it in the 94th 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-2016-4567?

CVE-2016-4567 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-2016-4567 published, and has it been updated?

CVE-2016-4567 was published on May 22, 2016 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm🐘 Packagist

Not in CISA KEV

MEDIUM severity

CVE-2016-4567 — mediaelement

MEDIUMFix: johndyer/mediaelement@34834ee

CVE-2016-4567 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in mediaelement. A fix is available for mediaelement — see the affected versions and patch details below.

MediaElement Vulnerable to Reflected XSS

Also known asGHSA-277w-qpxr-2549

Published

May 22, 2016

Updated

Oct 24, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

7.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs94th percentile — riskier than 94% of all scored CVEsHighest risk

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

3 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.

51other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

mediaelementnpm

24Kdownloads / week

Description

Cross-site scripting (XSS) vulnerability in flash/FlashMediaElement.as in MediaElement.js before 2.21.0, as used in WordPress before 4.5.2, allows remote attackers to inject arbitrary web script or HTML via an obfuscated form of the jsinitfunction parameter, as demonstrated by "jsinitfunctio%gn."

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`mediaelement`	all versions	2.11.1`npm install mediaelement@2.11.1`
🐘Packagist	`contao-components/mediaelement`	≥ 2.14.2&&< 2.21.1	2.21.1`composer require contao-components/mediaelement:^2.21.1`
🐘Packagist	`contao/core`	≥ 3.0.0&&< 3.5.15	3.5.15`composer require contao/core:^3.5.15`

Affected Products

2 products · 2 configurations

Application

mediaelement.jsmediaelementjs

≤ 2.20.1

range

Application

wordpresswordpress

≤ 4.5.1

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mediaelement, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mediaelement to 2.11.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-4567 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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