CVE-2021-39197 Information

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.

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Reference

https://github.com/BetterErrors/better_errors/commit/8e8e796bfbde4aa088741823c8a3fc6df2089bb0 https://github.com/BetterErrors/better_errors/security/advisories/GHSA-w3j4-76qw-wwjm https://github.com/BetterErrors/better_errors/pull/474 https://github.com/BetterErrors/better_errors/discussions/507

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

REQUIRED

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

8.8