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Vulnerability · Published Sep 7, 2021 · Assigned by GitHub_M

CVE-2021-39197Cross-Site Request Forgery in better_errors

Medium 6.3

In plain English

A medium-severity cross-site request forgery in better_errors from BetterErrors. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 51% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.3Medium
Exploit odds (30 days)0.6%top 49.1% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official 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 workarounds to mitigate the risk of using older releases of better_errors.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
RubyGemsbetter_errors2.8.0GHSA-w3j4-76qw-wwjm

Affected products (as reported)

VendorProductVersions
BetterErrors better_errors < 2.8.0

Weakness: CWE-352 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

References