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Description

Concrete CMS 9.5.0 and below is vulnerable to CSRF via Backend\File::approveVersion. Victim with edit_file_contents permission is CSRF'd into publishing an attacker-chosen previously-uploaded version (downgrade to an older version of a file, or activation of a co-editor's unpublished version). The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

PUBLISHED Reserved 2026-05-11 | Published 2026-05-22 | Updated 2026-05-22 | Assigner ConcreteCMS




LOW: 2.3CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Problem types

CWE-352 Cross-Site request forgery (CSRF)

Product status

Default status
unaffected

5.0 (git)
affected

Credits

Winston Crooker finder

References

documentation.concretecms.org/...n-history/951-release-notes release-notes

cve.org (CVE-2026-8340)

nvd.nist.gov (CVE-2026-8340)

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