What’s Vulnerable › Vulnerabilities

CVE-2021-40108

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-09-27 · updated 2026-06-17
• Weakness: CWE-352

Description

An issue was discovered in Concrete CMS through 8.5.5. The Calendar is vulnerable to CSRF. ccm_token is not verified on the ccm/calendar/dialogs/event/add/save endpoint.

Affected products

• Concrete CMS: before 8.5.6 — fixed in 8.5.6

How to fix

Upgrade to a fixed version: Concrete CMS 8.5.6. Check the vendor advisory for mitigations.

References

• https://documentation.concretecms.org/developers/introduction/version-history/856-release-notes
• https://hackerone.com/reports/1102018
• https://documentation.concretecms.org/developers/introduction/version-history/856-release-notes
• https://hackerone.com/reports/1102018

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