CVE-2021-39197
6.3 · MEDIUMOverview
CVE-2021-39197 is a medium-severity vulnerability affecting better_errors_project better_errors. It was published on September 7, 2021 and has a CVSS 3.1 base score of 6.3 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 6.3, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
Technical Description
better_errors is an open source replacement for the standard Rails error page with more information rich error pages. It is also usable outside of Rails in any Rack app as Rack middleware. better_errors prior to 2.8.0 did not implement CSRF protection for its internal requests. It also did not enforce the correct "Content-Type" header for these requests, which allowed a cross-origin "simple request" to be made without CORS protection. These together left an application with better_errors enabled open to cross-origin attacks. As a developer tool, better_errors documentation strongly recommends addition only to the `development` bundle group, so this vulnerability should only affect development environments. Please ensure that your project limits better_errors to the `development` group (or the non-Rails equivalent). Starting with release 2.8.x, CSRF protection is enforced. It is recommended that you upgrade to the latest release, or minimally to "~> 2.8.3". There are no known workaround
Remediation
Check the references section for vendor advisories and patches from better_errors_project. Update better_errors to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| better_errors_project | better_errors | >= 0, < 2.8.0 | Affected |
References
Frequently Asked Questions
What is CVE-2021-39197?
CVE-2021-39197 is a medium-severity vulnerability affecting better_errors_project better_errors. It was published on September 7, 2021 and has a CVSS 3.1 base score of 6.3 (MEDIUM).
How severe is CVE-2021-39197?
This vulnerability has a CVSS 3.1 base score of 6.3, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2021-39197?
Check the references section for vendor advisories and patches from better_errors_project. Update better_errors to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-39197?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-39197 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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