Time-of-check Time-of-use (TOCTOU) Race Condition in Craft CMS - CVE-2026-27127
Published: April 17, 2026
Vulnerability identifier: #VU126482
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-27127
CWE-ID: CWE-367
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to bypass SSRF protections and disclose sensitive information.
The vulnerability exists due to time-of-check time-of-use (TOCTOU) race condition in the GraphQL Asset mutation resolver when validating a hostname separately from the subsequent HTTP request. A remote user can supply a URL that uses DNS rebinding to bypass SSRF protections and disclose sensitive information.
Exploitation requires GraphQL schema permissions to create or edit assets, or a public schema that is misconfigured with write permissions.
Affected software
Craft CMS
How to mitigate CVE-2026-27127
Install security update from vendor's website.
Craft CMS - addressed in versions 4.16.19, 5.8.23