CVE-2026-8337 - Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys when sites are running concurrent public surveys and private surveys

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MEDIUM

Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys when sites are running concurrent public surveys and private surveys

Published May 21, 2026

6.3

MEDIUM

CVSS 4.0

EPSS 0.32%

Description

Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys. To be vulnerable, a site would have to be configured in such a way that both public and private surveys are present on the site. An unauthenticated attacker can vote in the restricted survey by submitting the restricted optionID through the public survey’s endpoint. 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:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Zer0daySec https://github.com/Zee99y for reporting

Affected products

Vendor Concrete CMS Product Concrete CMS Default
unaffected
- Version
  5.0
  Status
  affected
  Constraints
  <=9.5.0

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Concrete CMS

unaffected

Version	Status	Constraints
5.0	affected	<=9.5.0

Remediation

No remediation recorded yet.

Weaknesses (2)

CWE-565

CWE-639

Authorization Bypass

References (3)

https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes
release-notesRelease Notes
https://github.com/advisories/GHSA-8c7c-h7px-267g
Advisory
https://nvd.nist.gov/vuln/detail/CVE-2026-8337

Link	Providers	Tags
https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes		release-notesRelease Notes
https://github.com/advisories/GHSA-8c7c-h7px-267g		Advisory
https://nvd.nist.gov/vuln/detail/CVE-2026-8337