CVE-2026-8240 Concrete CMS 9.5.0 and below is vulnerable to unauthenticated page metadata disclosure in Backend\SummaryTemplate

What is CVE-2026-8240?

CVE-2026-8240 is a medium-severity vulnerability in Concretecms Concrete Cms, published on 21 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Concrete CMS 9.5.0 and below is vulnerable to unauthenticated page metadata disclosure across every page with a configured summary template, revealing the existence of private, draft, and restricted pages while leaking title, path, description, and author information. 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:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Weakness: CWE-284

Which versions are affected by CVE-2026-8240?

2 open source packages ship an affected version, including concrete5/concrete5. It affects 1 product.

Products include Concretecms Concrete Cms.

How do I fix CVE-2026-8240?

Upgrade concrete5/concrete5 to 9.5.1 or later.

Is CVE-2026-8240 being exploited?

There is no known exploitation of CVE-2026-8240 in the wild and no public exploit code.

Other vulnerabilities in Concretecms Concrete Cms

• CVE-2023-48648 Concrete CMS allows unauthorized access because directories can be created with insecure permissions Critical 9.8
• CVE-2022-21829 Code injection in concrete CMS Critical 9.8
• CVE-2021-22958 Server-Side Request Forgery vulnerability in concrete5 Critical 9.8
• CVE-2021-40098 Path traversal in n/a Critical 9.8
• CVE-2026-8134 Concrete CMS Vulnerable to Relative Path Traversal Critical 9.4

All Concretecms Concrete Cms vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-vpgr-cwfx-pwfw.