CVE-2026-81926 Concrete CMS CVE debrief

Who should care

Concrete CMS administrators and editors who need to assess exposure and apply patches or workarounds to prevent script execution in authenticated sessions. They should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. They should also plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Why it matters

A low-severity vulnerability in Concrete CMS 9.4.0-9.5.2 allows an authenticated attacker to execute script in the editor's browser session via a crafted page path. Defenders should assess exposure, apply patches or workarounds, and monitor for suspicious activity in authenticated sessions.

• An attacker could execute script in an authenticated editor's browser session, potentially leading to unauthorized actions or data access.
• The vulnerability requires an authenticated user with high privileges to exploit, limiting its impact.
• The CVSS v4.0 score of 2.0 indicates a low-severity vulnerability, but defenders should still assess exposure and apply patches or workarounds.

Technical summary

The location panel's duplicate-path confirmation dialog in Concrete CMS 9.4.0-9.5.2 did not escape colliding page paths, allowing an authenticated attacker to execute script in the editor's browser session via a crafted page path. The vulnerability requires an authenticated user with high privileges to exploit, limiting its impact. The CVSS v4.0 score of 2.0 indicates a low-severity vulnerability, but defenders should still assess exposure and apply patches or workarounds to prevent script execution in authenticated sessions.

Defensive priority

Assess exposure and apply patches or workarounds to prevent script execution in authenticated sessions.

Recommended defensive actions

• Inventory Concrete CMS installations to identify potential exposure
• Verify and apply patches or workarounds to prevent script execution
• Monitor for suspicious activity in authenticated sessions
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability was reported by Yonatan Drori from Tenzai and assigned a CVSS v4.0 score of 2.0. The NVD entry is currently Analyzed. The vulnerability affects Concrete CMS versions 9.4.0 through 9.5.2. The location panel's duplicate-path confirmation dialog did not escape colliding page paths, allowing an authenticated attacker to execute script in the editor's browser session via a crafted page path. The official CVE Program record and NVD detail page provide additional information.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.