Security readout for executives and security teams
Plain-English summary
Concrete CMS through 8.5.5 has a Calendar CSRF flaw. If an authenticated CMS user is tricked into visiting attacker-controlled content, the site may accept an unwanted calendar event save request as that user. The public data does not provide CVSS scoring or confirmed business impact beyond the Calendar endpoint.
Executive priority
Treat as a targeted web application integrity risk, not a confirmed emergency. Prioritize remediation for public CMS sites, sites with many editors, or business workflows relying on calendar content.
Technical view
The reported issue is missing ccm_token verification on ccm/calendar/dialogs/event/add/save in Concrete CMS through 8.5.5. This weakens CSRF protection for Calendar event creation or save behavior. Source data does not include CVSS, CWE, exploit details, or exact role requirements.
Likely exposure
Exposure is most likely for Concrete CMS deployments at version 8.5.5 or earlier that use the Calendar feature and have authenticated users with calendar event permissions.
Exploitation context
The CVE source bundle does not show CISA KEV listing or confirmed active exploitation. The public HackerOne reference indicates reported vulnerability context, but the supplied data does not establish real-world exploitation.
Researcher notes
Evidence is narrow: missing token verification is named for one Calendar endpoint. Avoid assuming broader Concrete CMS compromise, unauthenticated exploitation, or data theft without further vendor or advisory detail.
Mitigation direction
- Identify Concrete CMS instances running 8.5.5 or earlier.
- Review Concrete CMS 8.5.6 release notes and vendor upgrade guidance.
- Upgrade affected Concrete CMS installations when vendor guidance confirms the fix path.
- Limit calendar-management permissions to trusted users until remediated.
- Educate CMS users to avoid untrusted links while logged in.
Validation and detection
- Inventory Concrete CMS versions across internet-facing and internal sites.
- Check whether the Calendar feature is enabled on affected deployments.
- Confirm whether ccm/calendar/dialogs/event/add/save requires valid CSRF token protection after remediation.
- Review access logs for unexpected calendar event creation activity.
- Verify only intended roles can create or save calendar events.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-40108 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://hackerone.com/reports/1102018CVE reference · x_refsource_MISC
- https://documentation.concretecms.org/developers/introduction/version-history/856-release-notesCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.