CVE-2026-7888: high-severity vulnerability in Concrete CMS
Concrete CMS below 9.5.3 is vulnerable to PHP Object Injection via unserialize() calls in the Workflow, Form block, and File/Set components that lack the allowed_classes restriction.
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.4epss 0.2%
Concrete CMS below 9.5.3 is vulnerable to PHP Object Injection via unserialize()
calls in the Workflow, Form block, and File/Set components that lack the
allowed_classes restriction. The Form block and File/Set sinks were addressed in
9.5.2; the Workflow component sinks were addressed in 9.5.3. An unauthenticated
attacker may trigger arbitrary PHP object instantiation if a malicious serialized
payload has been placed in the database. Thanks XananasX7 and Sanjorn Keeratirungsan
(dizconnect) for independently reporting the original components, and sh4d0byss for
reporting the Workflow component wasn't fixed in 9.5.2. The Concrete CMS security team gave this
vulnerability a CVSS v.4.0 score of 8.4 with vector CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/
VC:H/VI:H/VA:H/SC:N/SI:N/SA:N.
CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Affected products
Concrete CMS · Concrete CMSRelated CVEs — Concrete CMS
In the same product, most dangerous first.
CVE-2026-18110HIGHConcrete CMS 9.0.0 through 9.5.2 is vulnerable to missing authorization in the user selector autocomplete endpoint (/ccm/system/user/autocomplete), allowing an unauthenticated attacker to retrieve the complete backend user directory — internal ID, usernameEPSS 1.6%CVE-2026-6826MEDIUMConcrete 9.5.0 and below has file usage disclosure via missing permission check in Usage controllerEPSS 1.5%CVE-2024-1247LOWConcrete CMS version 9 before 9.2.5 vulnerable to stored XSS via the Role Name fieldEPSS 1.2%CVE-2026-8134CRITICALConcrete CMS 9.5.0 and below is vulnerable to Authenticated RCE via Composer customTemplate Path Traversal leading to PHP File InclusionEPSS 0.7%CVE-2026-3452HIGHConcrete CMS below 9.4.8 is vulnerable to stored deserialization leading to RCE in the Express Entry List block.EPSS 0.7%CVE-2011-3183—CVE-2011-3183EPSS 0.7%