HumHub Community Edition 1.18.4-pl1 - Reflected XSS in Space membership request button rendering (CVE-2026-18756) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-18756

HumHub Community Edition 1.18.4-pl1 - Reflected XSS in Space membership request button rendering

Answer in brief

CVE-2026-18756 records a Unknown severity vulnerability in HumHub Community Edition 1.18.4-pl1 - Reflected XSS in Space membership request button rendering. The current sources do not mark it as known exploited. The current feed maps HumHub/HumHub (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 19, 2026Updated Aug 19, 2026Source checked Aug 19, 2026First seen by HOL Aug 19, 2026Material review Aug 19, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps HumHub/HumHub (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
HumHub/HumHubgeneric	1.18.4	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for HumHub/HumHub.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 19, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.