{"id":"CVE-2020-5217","aliases":["GHSA-xq52-rv6w-397c"],"url":"https://o3.security/vulnerability/CVE-2020-5217","summary":"Directive injection when using dynamic overrides with user input","details":"### Impact\n\nIf user-supplied input was passed into `append/override_content_security_policy_directives`, a semicolon could be injected leading to directive injection.\n\nThis could be used to e.g. override a `script-src` directive. Duplicate directives are ignored and the first one wins. The directives in `secure_headers` are sorted alphabetically so they pretty much all come before `script-src`. A previously undefined directive would receive a value even if `SecureHeaders::OPT_OUT` was supplied.\n\nThe fixed versions will silently convert the semicolons to spaces and emit a deprecation warning when this happens. This will result in innocuous browser console messages if being exploited/accidentally used. In future releases, we will raise application errors resulting in 500s.\n\n> Duplicate script-src directives detected.  All but the first instance will be ignored.\n\nSee https://www.w3.org/TR/CSP3/#parse-serialized-policy\n\n> Note: In this case, the user agent SHOULD notify developers that a duplicate directive was ignored. A console warning might be appropriate, for example.\n\n### Patches\n\nDepending on what major version you are using, the fixed versions are 6.2.0, 5.1.0, 3.8.0.\n\n### Workarounds\n\nIf you are passing user input into the above methods, you could filter out the input:\n\n```ruby\noverride_content_security_policy_directives(:frame_src, [user_input.gsub(\";\", \" \")])\n```\n\n### References\n\nReported in https://github.com/twitter/secure_headers/issues/418\nhttps://www.w3.org/TR/CSP3/#parse-serialized-policy\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n* Open an issue in [this repo](https://github.com/twitter/secure_headers/issues/new)\n* DM @ndm on twitter ","published":"2020-01-23T03:15:10.793Z","modified":"2026-10-20T10:54:22.386859215Z","cvss":{"score":5.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N"},"epss":{"score":0.0183,"percentile":0.77774,"asOf":"2026-09-16"},"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"RubyGems","name":"secure_headers","fixedVersion":"6.2.0"},{"ecosystem":"RubyGems","name":"secure_headers","fixedVersion":"5.1.0"},{"ecosystem":"RubyGems","name":"secure_headers","fixedVersion":"3.8.0"}],"fix":{"url":"https://github.com/twitter/secure_headers/commit/936a160e3e9659737a9f9eafce13eea36b5c9fa3","label":"twitter/secure_headers@936a160"},"references":[{"type":"ADVISORY","url":"https://github.com/twitter/secure_headers/pull/421"},{"type":"ADVISORY","url":"https://github.com/twitter/secure_headers/security/advisories/GHSA-xq52-rv6w-397c"},{"type":"FIX","url":"https://github.com/twitter/secure_headers/commit/936a160e3e9659737a9f9eafce13eea36b5c9fa3"},{"type":"EVIDENCE","url":"https://github.com/twitter/secure_headers/issues/418"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2020-5217"},{"type":"WEB","url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/secure_headers/CVE-2020-5217.yml"},{"type":"PACKAGE","url":"https://github.com/twitter/secure_headers"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-20T10:54:22.386859215Z"}}