CVE-2026-18756

HIGH
MEDIUM Priority: 0.03 BB Relevance: 54/100
Published: 2026-08-19 Modified: 2026-10-27 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity Conf. Impact Integ. Impact

CVSS Vector Breakdown

AV: Network
AC: Low
PR: Low
UI: Active
S: X
AT: Present
VC: High
VI: High
VA: None

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.

Weakness Classification (1)

Bug Bounty Relevance

54 / 100
✓ Network accessible
✓ Low complexity

CVSS Score

7.2 / 10.0 v4.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — Exploitation Probability

0.47%
Raw Score 0.004670
Percentile 40.4%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00467
2026-10-28
0.00467

Intelligence Sources

nvd ref →