What’s Vulnerable › Vulnerabilities

CVE-2026-18756: HumHub Community Edition 1.18.4-pl1 - Reflected XSS in Space membership request button rendering

• Severity: high (CVSS 7.2 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-19 · updated 2026-10-27
• Weakness: CWE-79

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.

Affected products

• humhub: 1.18.4

References

• https://fluidattacks.com/es/advisories/turizo
• https://github.com/humhub/humhub
• https://github.com/humhub/humhub/pull/8381

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