Answer in brief
CVE-2026-81904 records a Medium severity (CVSS 6.3) 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), 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.
CVSS is 6.3. 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.
The current feed maps Concrete CMS/Concrete CMS (generic), Concrete CMS/Concrete CMS (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Concrete CMS/Concrete CMSgeneric | 5 | Not reported |
| Concrete CMS/Concrete CMSgeneric | >=5 <=9.5.2 | Not reported |
Published upstream
Sep 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 10, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 8, 2026
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.