CVE-2026-18756

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.

CVSS 4.0

7.2CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N

EPSS

0.5% chance of exploitation in the next 30 days; higher than 40% of CVEs (scores of 2026-10-26)

CWE

CWE-79

Published

2026-08-19

Modified

2026-10-27

Record from

the NVD, synced 2026-10-27

References

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

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