CVE-2026-81895
concretecms concrete cms
Summary
In Concrete CMS before 9.5.3, the Document Library block stored the file-set identifiers submitted through fsID[] without validating them as integers, and when the block was configured with setMode set to any it concatenated each stored identifier directly into the file-set filter query instead of casting it or binding it as a parameter. An authenticated user permitted to add or edit a Document Library block could therefore persist SQL syntax in the block configuration (btDocumentLibrary.setIds), and that stored expression was executed every time the published page containing the block was rendered, producing stored, time-based blind SQL injection. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 8.5 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Habib Allah 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 · SQL injection medium confidence
What to look for
- SQL syntax in parameters (UNION SELECT, ' OR 1=1, SLEEP(, WAITFOR DELAY, xp_cmdshell)
- Bursts of 500 errors or very slow responses from the same client (blind injection)
- Database processes (sqlservr.exe, postgres, mysqld) spawning shells
- 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
A generic baseline worked out from the product type and weakness (CWE-89), not a detection. Check table and field names against your environment. Hunt queries for Sigma, Splunk, Sentinel and CrowdStrike are coming.