CVE-2026-3241mediumCWE-79

CVE-2026-3241: medium-severity vulnerability in Concrete CMS

Concrete CMS below version 9.4.8 is vulnerable to a stored cross-site scripting (XSS) in the "Legacy Form" block.

Published

Follow this CVE+ Monitor Concrete CMS+ Monitor concrete5/concrete5

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 4.8epss 0.2%
In Concrete CMS below version 9.4.8, a stored cross-site scripting (XSS) vulnerability exists in the "Legacy Form" block. An authenticated user with permissions to create or edit forms (e.g., a rogue administrator) can inject a persistent JavaScript payload into the options of a multiple-choice question (Checkbox List, Radio Buttons, or Select Box). This payload is then executed in the browser of any user who views the page containing the form. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 4.8 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks M3dium for reporting.
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Affected products
Concrete CMS · Concrete CMS
Related 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%