GHSA-277w-qpxr-2549 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
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.
How urgent is this, really
GHSA-277w-qpxr-2549 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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.
mediaelementnpmDescription
Cross-site scripting (XSS) vulnerability in flash/FlashMediaElement.swf 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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | mediaelement | all versions | 2.11.1npm install mediaelement@2.11.1 |
| 🐘Packagist | contao-components/mediaelement | ≥ 2.14.2&&< 2.21.1 | 2.21.1composer require contao-components/mediaelement:^2.21.1 |
| 🐘Packagist | contao/core | ≥ 3.0.0&&< 3.5.15 | 3.5.15composer require contao/core:^3.5.15 |
Detection & mitigation playbook
Open-source dependencyDetect
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 GHSA-277w-qpxr-2549 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 GHSA-277w-qpxr-2549 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-277w-qpxr-2549. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-277w-qpxr-2549 in your dependencies?
O3 Security finds GHSA-277w-qpxr-2549 across npm, Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.