CVE-2026-55691 EmbedVideo MediaWiki - Stored XSS

EmbedVideo MediaWiki extension < 4.1.0 contains a stored XSS caused by unsanitized user-supplied class value passed to sprintf in EmbedHtmlFormatter::toHtml, letting authenticated wiki editors execute arbitrary JavaScript for page visitors.

CVSS base score 8.6 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.48% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Stored XSS
Impact
Stored XSS
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
Published
15 September 2026
Updated
15 October 2026
Weakness
CWE-79

Vendor fix

Update to version 4.1.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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