CVE-2026-18423
concretecms concrete cms
Summary
Concrete CMS 9.0.0 through 9.5.2 is vulnerable to Insecure direct object reference (IDOR) in the Express saved search preset delete and edit dialogs . An authenticated user holding only view permission on a single Express entity could therefore permanently delete, with no undo, or rename saved search presets owned by Express entities for which they had no permission, and a renamed preset name was displayed back to users of the targeted entity, enabling defacement or social engineering. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N. Thanks Yalguun Tumenkhuu ( fg0x0 ) for reporting.
Published 2026-09-15 · first seen here 2026-10-10
Analysis & write-ups
No technical write-up from a research team yet. Contact Zero checks Unit 42, Google/Mandiant, Microsoft, Talos, CrowdStrike, Rapid7, watchTowr and others several times a day, plus NVD and CISA reference links.
Where it shows in your logs
Server or web application · Authentication bypass or missing authorisation medium confidence
What to look for
- Admin or API actions with no successful login before them in the same session
- New admin accounts, API keys or tokens created shortly after unusual requests
- Requests to admin or API endpoints from internet IPs
- The application's process (w3wp.exe, java, tomcat, node, php-fpm, httpd, python) starting shells or LOLBins (cmd, powershell, sh, bash, curl, wget, certutil)
- New script files in web roots (.jsp, .aspx, .php): a web shell
- Requests to unusual URLs on the application from internet IPs right before any of the above
- Outbound connections from the server to new external IPs
Data sources
Web server and WAF logs · ATT&CK DS0015 Application Log Content
- Sentinel
W3CIISLogAppServiceHTTPLogsAzureDiagnostics (Application Gateway / Front Door WAF)_Im_WebSession- Splunk
Web.Webms:iis:autoaccess_combinedWAF / proxy sourcetypes- CrowdStrike
Falcon Next-Gen SIEM: third-party web / WAF / proxy logs
Process creation · ATT&CK DS0009 Process Creation
- Sentinel
DeviceProcessEventsSecurityEvent (4688)Sysmon Event ID 1_Im_ProcessCreate- Splunk
Endpoint.ProcessesXmlWinEventLog:Microsoft-Windows-Sysmon/OperationalWinEventLog:Security (4688)- CrowdStrike
ProcessRollup2SyntheticProcessRollup2
File creation · ATT&CK DS0022 File Creation
- Sentinel
DeviceFileEventsSysmon Event ID 11_Im_FileEvent- Splunk
Endpoint.FilesystemSysmon Event ID 11- CrowdStrike
NewExecutableWrittenNewScriptWritten*FileWritten events
Network connections · ATT&CK DS0029 Network Connection Creation / Network Traffic Flow
- Sentinel
DeviceNetworkEventsCommonSecurityLog (firewall)_Im_NetworkSession- Splunk
Network_Traffic.All_TrafficFirewall sourcetypes (pan:traffic, fortigate_traffic, cisco:asa)- CrowdStrike
NetworkConnectIP4NetworkReceiveAcceptIP4NetworkConnectIP6
Authentication and sessions · ATT&CK DS0028 Logon Session Creation / DS0002 User Account Authentication
- Sentinel
SigninLogsSecurityEvent (4624, 4625, 4648)DeviceLogonEventsIdentityLogonEvents_Im_Authentication- Splunk
Authentication.Authenticationpan:globalprotectVPN sourcetypes- CrowdStrike
UserLogonUserLogonFailed2Falcon Identity Protection events
Account and group changes · ATT&CK DS0002 User Account Creation / Modification
- Sentinel
SecurityEvent (4720, 4728, 4732, 4756)AuditLogsIdentityDirectoryEvents- Splunk
Change.All_Changes (Account_Management)WinEventLog:Security (4720, 4732)- CrowdStrike
UserAccountCreatedUserAccountAddedToGroup
A generic baseline worked out from the product type and weakness (CWE-639), not a detection. Check table and field names against your environment. Hunt queries for Sigma, Splunk, Sentinel and CrowdStrike are coming.