CVE-2021-40109

6.4 MEDIUM

A SSRF issue was discovered in Concrete CMS through 8.5.5

Published: 2021-09-27 · Last updated: 2026-06-17

Severity and scoring

CVSS: 6.4 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
CWE: CWE-918

Affected products

Vendor	Product
concretecms	concrete_cms

Description

A SSRF issue was discovered in Concrete CMS through 8.5.5. Users can access forbidden files on their local network. A user with permissions to upload files from external sites can upload a URL that redirects to an internal resource of any file type. The redirect is followed and loads the contents of the file from the redirected-to server. Files of disallowed types can be uploaded.

Source: NVD

References

[NVD]https://nvd.nist.gov/vuln/detail/CVE-2021-40109
[Vendor advisory]https://documentation.concretecms.org/developers/introduction/version-history/856-release-notes
[Other]https://hackerone.com/reports/1102105
[Vendor advisory]https://documentation.concretecms.org/developers/introduction/version-history/856-release-notes
[Other]https://hackerone.com/reports/1102105

Related CVEs

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CVE-2026-8340 — Concrete CMS 9.5.0 and below is vulnerable to CSRF via Backend\File::approveVersion (4.3 MEDIUM)
CVE-2026-8434 — Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/backend/file rescanMultiple() (8.8 HIGH)
CVE-2026-8433 — Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/backend/file rescan() (8.8 HIGH)
CVE-2026-8432 — Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/backend/file star() (8.8 HIGH)
CVE-2026-8427 — Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/backend/file removeFavoriteFolder(... (8.8 HIGH)

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