Time-of-check Time-of-use (TOCTOU) Race Condition in Craft CMS - CVE-2026-27128
Published: April 17, 2026
Vulnerability identifier: #VU126478
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-27128
CWE-ID: CWE-367
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Pixel & Tonic, Inc.
Affected software:
Craft CMS
Craft CMS
Detailed vulnerability description
The vulnerability allows a remote user to escalate privileges.
The vulnerability exists due to a time-of-check time-of-use (TOCTOU) race condition in the token validation service when handling concurrent requests for limited-usage impersonation tokens. A remote user can send concurrent requests using a valid impersonation URL to escalate privileges.
Exploitation requires obtaining a non-expired impersonation URL via some other means and bypassing any rate-limiting rules in place.
How to mitigate CVE-2026-27128
Install security update from vendor's website.