CVE-2026-100238 Flow colon-separator and flow-guidedtour-optin-welcome-description messages allow stored XSS
Stored XSS in MediaWiki Flow Extension allows attackers to inject scripts via colon-separator and opt-in messages, potentially compromising user sessions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-100238?
CVE-2026-100238 is a medium-severity cross-site scripting vulnerability in Wikimedia Foundation Mediawiki - Flow Extension, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-100238?
How do I fix CVE-2026-100238?
No fix has been published for CVE-2026-100238 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-100238 being exploited?
There is no known exploitation of CVE-2026-100238 in the wild and no public exploit code.
Sources
Also known as GHSA-hg46-8gx2-qp79.