Summary
Craft CMS Race condition in Token Service potentially allows for token usage greater than the token limit
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.
References
https://github.com/craftcms/cms/commit/3e4afe18279951c024c64896aa2b93cda6d95fdf
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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craftcms/cms to 4.16.19 or later; craftcms/cms to 5.8.23 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-27128? CVE-2026-27128 is a medium-severity security vulnerability in craftcms/cms (composer), affecting versions >= 4.5.0-RC1, <= 4.16.18. It is fixed in 4.16.19, 5.8.23.
- Which versions of craftcms/cms are affected by CVE-2026-27128? craftcms/cms (composer) versions >= 4.5.0-RC1, <= 4.16.18 is affected.
- Is there a fix for CVE-2026-27128? Yes. CVE-2026-27128 is fixed in 4.16.19, 5.8.23. Upgrade to this version or later.
- Is CVE-2026-27128 exploitable, and should I be worried? Whether CVE-2026-27128 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-27128 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-27128?
- Upgrade
craftcms/cmsto 4.16.19 or later - Upgrade
craftcms/cmsto 5.8.23 or later
- Upgrade