PT-2026-42772 · Unknown · Concrete Cms

Winston Crooker · CVE-2026-8340 · Published 2026-05-22 · Updated 2026-05-26

Positive Technologies (AI Summary)

CVSS v3.1

4.3

Medium

Base vector

AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Name of the Vulnerable Software and Affected Versions Concrete CMS versions prior to 9.5.1

Description Cross-Site Request Forgery (CSRF) occurs via the approveVersion() function within the BackendFile class. An attacker can trick a user with edit file contents permissions into publishing a previously uploaded version of a file. This allows for the activation of an unpublished version from a co-editor or a downgrade to an older file version.

Recommendations Update Concrete CMS to version 9.5.1 or later.

Exploit

Fix

CSRF

Weakness Enumeration

CWE-352

Related Identifiers

CVE-2026-8340

GHSA-XJG6-5V39-V7FC

Affected Products

Concrete Cms

References · 6

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/8xxx/CVE-2026-8340.json · Exploit
• https://nvd.nist.gov/vuln/detail/CVE-2026-8340 · Security Note
• https://osv.dev/vulnerability/CVE-2026-8340 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-xjg6-5v39-v7fc · Vendor Advisory
• https://github.com/concretecms/concretecms · Note
• https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes · Note