CVE-2019-5421 is a medium-severity security vulnerability in devise (rubygems), affecting versions < 4.6.0. It is fixed in 4.6.0.
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 incrementfailedattempts within the Devise::Models::Lockable class not being concurrency safe.
rubygems
devise (< 4.6.0)devise → 4.6.0 (rubygems)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 instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2019-5421 is reachable in your applications. Explore open-source security for your team.
See if CVE-2019-5421 is reachable in your applications. Get a demo
Upgrade devise to 4.6.0 or later to resolve this vulnerability.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2019-5421 is a medium-severity security vulnerability in devise (rubygems), affecting versions < 4.6.0. It is fixed in 4.6.0.
devise (rubygems) versions < 4.6.0 is affected.
Yes. CVE-2019-5421 is fixed in 4.6.0. Upgrade to this version or later.
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
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.
Upgrade devise to 4.6.0 or later.