CVE-2026-100238: Flow colon-separator and flow-guidedtour-optin-welcome-description messages allow stored XSS

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-29 · updated 2026-09-30
Weakness: CWE-79

Description

Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Wikimedia Foundation Mediawiki - Flow Extension allows Stored XSS. This issue affects Mediawiki - Flow Extension: from * before 1.46.1, 1.45.5, 1.43.10.

Affected products

Wikimedia Foundation Mediawiki - Flow Extension: before 1.46.1, 1.45.5, 1.43.10 — fixed in 1.43.10, 1.45.5, 1.46.1

How to fix

Upgrade to a fixed version: Wikimedia Foundation Mediawiki - Flow Extension 1.43.10, 1.45.5, 1.46.1. Check the vendor advisory for mitigations.

References

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