CVE-2026-18526 HumHub 1.18.4 / 1.18.4-pl1 – Stored Cross-Site Scripting in oEmbed confirmation
Attackers can inject malicious scripts via oEmbed confirmation, potentially stealing user sessions or executing code in HumHub.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-18526?
CVE-2026-18526 is a high-severity cross-site scripting vulnerability in HumHub, published on 19 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
HumHub Community Edition 1.18.4 and 1.18.4-pl1 contain a stored Cross-Site Scripting (XSS) vulnerability in the oEmbed confirmation rendering workflow.
Weakness: CWE-79
Which versions are affected by CVE-2026-18526?
How do I fix CVE-2026-18526?
No fix has been published for CVE-2026-18526 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-2026-18526 being exploited?
There is no known exploitation of CVE-2026-18526 in the wild and no public exploit code.