An issue was discovered in Concrete CMS through 8.5.5.
Priority LOW 28CWE-79Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-79.
Summary
An issue was discovered in Concrete CMS through 8.5.5. There is XSS via Markdown Comments.
Why it matters now
EPSS 0.00651 51st percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:* | up to 8.5.5 | Vulnerable | Concrete CMS |
- cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:* Versions up to 8.5.5 Vulnerable ·Concrete CMS
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2021-40105
- 2026-10-03 Alias added: GHSA-5x56-gcx7-98rh
- 2026-10-14 EPSS moved to the 50th–90th percentile
References
More Concrete Cms vulnerabilities
- TI-2026-23602 ConcreteCMS v9.4.7 contains a Denial of Service (DoS) vulnerability in the File Manager… CVSS 3.1MEDIUM 6.5
- TI-2023-23992 A Cross Site Scripting (XSS) vulnerability in Concrete CMS from versions 9.2.0 to 9.2.2… CVSS 3.1MEDIUM 5.4
- TI-2023-26495 Concrete CMS before 8.5.13 and 9.x before 9.2.2 allows unauthorized access because… CVSS 3.1CRITICAL 9.8
- TI-2026-14907 Missing authorization in Concrete CMS CVSS 4.0HIGH 8.7
- TI-2022-06200 Cleartext transmission of sensitive information in https://github.com/concrete5/concrete5 CVSS 3.1CRITICAL 9.8
- TI-2021-17294 An issue was discovered in Concrete CMS through 8.5.5. CVSS 3.1CRITICAL 9.8
Sources
- CVE-2021-40105 · CVE Program
- CVE-2021-40105 · NVD
- FIRST EPSS
- GHSA-5x56-gcx7-98rh · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences