Summary
devise Time-of-check Time-of-use Race Condition vulnerability
Devise ruby gem before 4.6.0 when the lockable module is used is vulnerable to a time-of-check time-of-use (TOCTOU) race condition due to increment_failed_attempts within the Devise::Models::Lockable class not being concurrency safe.
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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Frequently Asked Questions
- What is CVE-2019-5421? CVE-2019-5421 is a medium-severity security vulnerability in devise (rubygems), affecting versions < 4.6.0. It is fixed in 4.6.0.
- Which versions of devise are affected by CVE-2019-5421? devise (rubygems) versions < 4.6.0 is affected.
- Is there a fix for CVE-2019-5421? Yes. CVE-2019-5421 is fixed in 4.6.0. Upgrade to this version or later.
- Is CVE-2019-5421 exploitable, and should I be worried? Whether CVE-2019-5421 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-2019-5421 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-2019-5421? Upgrade
deviseto 4.6.0 or later.