Summary
Exposure of Sensitive Information to an Unauthorized Actor in activestorage
A bypass vulnerability in Active Storage >= 5.2.0 for Google Cloud Storage and Disk services allow an attacker to modify the content-disposition and content-type parameters which can be used in with HTML files and have them executed inline. Additionally, if combined with other techniques such as cookie bombing and specially crafted AppCache manifests, an attacker can gain access to private signed URLs within a specific storage path.
Vulnerable apps are those using either GCS or the Disk service in production. Other storage services such as S3 or Azure aren't affected.
Impact
CVE-2018-16477 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.2.1.1); upgrading removes the vulnerable code path.
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-2018-16477? CVE-2018-16477 is a medium-severity security vulnerability in activestorage (rubygems), affecting versions >= 5.2.0, <= 5.2.1.0. It is fixed in 5.2.1.1.
- How severe is CVE-2018-16477? CVE-2018-16477 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of activestorage are affected by CVE-2018-16477? activestorage (rubygems) versions >= 5.2.0, <= 5.2.1.0 is affected.
- Is there a fix for CVE-2018-16477? Yes. CVE-2018-16477 is fixed in 5.2.1.1. Upgrade to this version or later.
- Is CVE-2018-16477 exploitable, and should I be worried? Whether CVE-2018-16477 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-2018-16477 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-2018-16477? Upgrade
activestorageto 5.2.1.1 or later.