CVE-2026-18430 HumHub 1.18.4 - Stored XSS in comment-deletion notifications through unescaped administrator reason
A space administrator can inject malicious scripts via the comment deletion reason, leading to stored XSS in notifications.
- 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-2026-18430?
CVE-2026-18430 is a high-severity cross-site scripting vulnerability in HumHub, published on 19 Aug 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
HumHub 1.18.4 contains a stored cross-site scripting vulnerability in the comment-deletion notification flow. A Space administrator can delete another user's comment, choose to notify the original author, and place HTML/JavaScript in the deletion reason.
Weakness: CWE-79
Which versions are affected by CVE-2026-18430?
How do I fix CVE-2026-18430?
No fix has been published for CVE-2026-18430 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-2026-18430 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-18430 exists.