MediaElement Vulnerable to Reflected XSS

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.1 · CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2016-4567: 7.35% estimated exploitation activity in the next 30 days; percentile 94.41 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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."

Published by the source

17 May 2022, 03:35 UTC

Last modified by the source

25 Apr 2024, 21:57 UTC

Source last checked

26 Oct 2026, 12:30 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-277w-qpxr-2549

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-277w-qpxr-2549

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# Patch Next advisory brief: CVE-2016-4567

Advisory: MediaElement Vulnerable to Reflected XSS
IDs: CVE-2016-4567, GHSA-277w-qpxr-2549
Record: https://patchnext.com/advisories/cve-2016-4567 (revision 2, source checked 26 Oct 2026, 12:30 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: contao/core 3.5.15; mediaelement 2.11.1; contao-components/mediaelement 2.21.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist contao/core: affected >= 3.0.0, < 3.5.15; fixed in 3.5.15
- npm mediaelement: affected < 2.11.1; fixed in 2.11.1
- Packagist contao-components/mediaelement: affected >= 2.14.2, < 2.21.1; fixed in 2.21.1

## Suggested inspection (read-only)
- Packagist contao/core: check the installed version with your package manager.
- `npm ls mediaelement --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- Packagist contao-components/mediaelement: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on contao/core, mediaelement, contao-components/mediaelement.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-277w-qpxr-2549 (OSV record GHSA-277w-qpxr-2549 lists affected ranges: npm mediaelement >=0 =2.14.2 =3.0.0 <3.5.15 (fixed))
- Verified: https://github.com/advisories/GHSA-277w-qpxr-2549 (GitHub-reviewed advisory GHSA-277w-qpxr-2549 lists affected ranges: npm mediaelement >=0 =2.14.2 =3.0.0 <3.5.15)

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