Concrete CMS before 9.5.3 is vulnerable to Missing Authorization in Stack/Container Sub-Block Asset Registration (CVE-2026-81904) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-81904

Concrete CMS before 9.5.3 is vulnerable to Missing Authorization in Stack/Container Sub-Block Asset Registration

Answer in brief

CVE-2026-81904 records a Unknown severity vulnerability in Concrete CMS before 9.5.3 is vulnerable to Missing Authorization in Stack/Container Sub-Block Asset Registration. The current sources do not mark it as known exploited. The current feed maps Concrete CMS/Concrete CMS (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 Sep 8, 2026Updated Sep 8, 2026Source checked Sep 9, 2026First seen by HOL Sep 8, 2026Material review Sep 8, 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 Concrete CMS/Concrete CMS (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Concrete CMS/Concrete CMSgeneric	5	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Concrete CMS/Concrete CMS.
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
Sep 8, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 8, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 8, 2026

Sources and claim methodology

Source referencedocumentation.concretecms.org

Upstream source description

Concrete CMS below 9.5.3 registered view assets for every sub-block of a Stack, Container, or layout area without checking whether the requesting user could view that sub-block. An unauthenticated visitor could recover configuration values emitted by a restricted sub-block's asset registration — such as a site's configured Google Maps API key — from any public page embedding an affected Stack, Container, or layout area, despite the block-level permission restriction. Any sub-block type whose asset or header hooks output configuration values is affected. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori (Tenzai) for reporting.

Quoted source text, attributed separately from HOL analysis.