CVE-2021-39197.yml

---
gem: better_errors
cve: 2021-39197
ghsa: w3j4-76qw-wwjm
url: https://github.com/BetterErrors/better_errors/security/advisories/GHSA-w3j4-76qw-wwjm
title: Older releases of better_errors open to Cross-Site Request Forgery attack
date: 2021-09-07
description: |
  ### Impact
  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)._

  ### Patches
  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".

  ### Workarounds
  There are no known workarounds to mitigate the risk of using older releases of better_errors.

  ### References
  - Chris Moberly provided [an example attack that uses a now-patched vulnerability of webpack-dev-server in conjunction with Better Errors](https://about.gitlab.com/blog/2021/09/07/why-are-developers-vulnerable-to-driveby-attacks/)

  ### For more information
  If you have any questions or comments about this advisory, please
  - Add to the [discussion in better_errors](https://github.com/BetterErrors/better_errors/discussions/507)
  - Open an issue in [better_errors](https://github.com/BetterErrors/better_errors)
cvss_v3: 6.3
patched_versions:
  - ">= 2.8.0"