CVE-2026-18756
High
Description
HumHub Community Edition 1.18.4 contains a reflected cross-site scripting vulnerability in the Space membership-request workflow. An attacker can place attacker-controlled button configuration in the options query-string parameter of space/membership/request-membership-form, lure an authenticated non-member into submitting the legitimate membership request form, and cause the server to return JavaScript containing attacker-controlled code.
SeverityHigh
CVSS7.2
Exploit probability—
Product
HumHub
PublishedAug 19, 2026
First seenAug 19, 2026
Weakness typeCWE-79Cross-site scripting (XSS)
How to fix
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| HumHub HumHub | 1.18.4 | — |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
In the Intelligence 360 plan
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.