CVE-2026-27128
MEDIUM
GHSA-6fx5-5cw5-4897
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
Lifecycle Timeline
3Description
Craft is a content management system (CMS). In versions 4.5.0-RC1 through 4.16.18 and 5.0.0-RC1 through 5.8.22, a Time-of-Check-Time-of-Use (TOCTOU) race condition exists in Craft CMS’s token validation service for tokens that explicitly set a limited usage. The `getTokenRoute()` method reads a token’s usage count, checks if it’s within limits, then updates the database in separate non-atomic operations. By sending concurrent requests, an attacker can use a single-use impersonation token multiple times before the database update completes. To make this work, an attacker needs to obtain a valid user account impersonation URL with a non-expired token via some other means and exploit a race condition while bypassing any rate-limiting rules in place. For this to be a privilege escalation, the impersonation URL must include a token for a user account with more permissions than the current user. Versions 4.16.19 and 5.8.23 patch the issue.
Analysis
Multiple usage tokens in Craft CMS 4.5.0-RC1 through 4.16.18 and 5.0.0-RC1 through 5.8.22 can be consumed beyond their intended limits due to a race condition in token validation logic where usage checks and database updates are not atomic. An authenticated attacker with access to a valid impersonation token can exploit concurrent requests to bypass usage restrictions and reuse single-use tokens multiple times. …
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Remediation
Within 30 days: Identify affected systems running versions 4.5.0-RC1 and apply vendor patches as part of regular patch cycle. Vendor patch is available.
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External POC / Exploit Code
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