{"id":"GHSA-w3j4-76qw-wwjm","summary":"Older releases of better_errors open to Cross-Site Request Forgery attack","details":"### Impact\nbetter_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.\n\n_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)._\n\n### Patches\nStarting with release 2.8.x, CSRF protection is enforced. It is recommended that you upgrade to the latest release, or minimally to \"~\u003e 2.8.3\".\n\n### Workarounds\nThere are no known workarounds to mitigate the risk of using older releases of better_errors.\n\n### References\n- 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/)\n\n### For more information\nIf you have any questions or comments about this advisory, please\n- Add to the [discussion in better_errors](https://github.com/BetterErrors/better_errors/discussions/507)\n- Open an issue in [better_errors](https://github.com/BetterErrors/better_errors)\n","aliases":["CVE-2021-39197"],"modified":"2026-05-07T05:01:08.750340389Z","published":"2021-09-07T23:08:24Z","database_specific":{"nvd_published_at":"2021-09-07T18:15:00Z","cwe_ids":["CWE-352"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2021-09-07T17:58:52Z"},"references":[{"type":"WEB","url":"https://github.com/BetterErrors/better_errors/security/advisories/GHSA-w3j4-76qw-wwjm"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-39197"},{"type":"WEB","url":"https://github.com/BetterErrors/better_errors/pull/474"},{"type":"WEB","url":"https://github.com/BetterErrors/better_errors/commit/8e8e796bfbde4aa088741823c8a3fc6df2089bb0"},{"type":"PACKAGE","url":"https://github.com/BetterErrors/better_errors"},{"type":"WEB","url":"https://github.com/BetterErrors/better_errors/discussions/507"},{"type":"WEB","url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/better_errors/CVE-2021-39197.yml"}],"affected":[{"package":{"name":"better_errors","ecosystem":"RubyGems","purl":"pkg:gem/better_errors"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.8.0"}]}],"versions":["0.0.1","0.0.2","0.0.3","0.0.4","0.0.5","0.0.6","0.0.7","0.0.8","0.1.0","0.1.1","0.2.0","0.3.0","0.3.2","0.5.0","0.6.0","0.7.0","0.7.2","0.8.0","0.9.0","1.0.0","1.0.0.rc1","1.0.1","1.1.0","2.0.0","2.1.0","2.1.1","2.2.0","2.3.0","2.4.0","2.5.0","2.5.1","2.6.0","2.7.0","2.7.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/09/GHSA-w3j4-76qw-wwjm/GHSA-w3j4-76qw-wwjm.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N"}]}