CVE-2026-58034 Stored XSS through a system message when blocking a temporary account that's related to other temporary accounts
Stored XSS in CheckUser allows attackers to execute scripts when blocking related temporary accounts, potentially compromising user sessions.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-58034?
CVE-2026-58034 is a cross-site scripting vulnerability in Mediawiki Mediawiki, published on 1 Jul 2026. An attacker needs administrator access to exploit it, 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 CheckUser.
This vulnerability is associated with program files modules/ext.CheckUser.TempAccounts/components/blockConnectedTempAccountsField.Vue.
This issue affects CheckUser: from 1.46.0-rc.0 before 1.46.0.
Weakness: CWE-79
Which versions are affected by CVE-2026-58034?
It affects 1 product.
Products include Mediawiki Mediawiki.
How do I fix CVE-2026-58034?
No fix has been published for CVE-2026-58034 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-2026-58034 being exploited?
There is no known exploitation of CVE-2026-58034 in the wild and no public exploit code.
Other vulnerabilities in Mediawiki Mediawiki
Sources
Also known as GHSA-5m8f-rxqc-4gpj.