{"id":"CVE-2020-5255","aliases":["BIT-symfony-2020-5255","GHSA-mcx4-f5f5-4859"],"url":"https://o3.security/vulnerability/CVE-2020-5255","summary":"Prevent cache poisoning via a Response Content-Type header in Symfony","details":"In Symfony before versions 4.4.7 and 5.0.7, when a `Response` does not contain a `Content-Type` header, affected versions of Symfony can fallback to the format defined in the `Accept` header of the request, leading to a possible mismatch between the response's content and `Content-Type` header. When the response is cached, this can prevent the use of the website by other users. This has been patched in versions 4.4.7 and 5.0.7.","published":"2020-03-30T20:15:19.570Z","modified":"2026-08-07T15:13:45.945709Z","cvss":{"score":4.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"symfony/http-foundation","fixedVersion":"4.4.7"},{"ecosystem":"Packagist","name":"symfony/http-foundation","fixedVersion":"5.0.7"},{"ecosystem":"Packagist","name":"symfony/symfony","fixedVersion":"4.4.7"},{"ecosystem":"Packagist","name":"symfony/symfony","fixedVersion":"5.0.7"}],"fix":{"url":"https://github.com/symfony/symfony/commit/dca343442e6a954f96a2609e7b4e9c21ed6d74e6","label":"symfony/symfony@dca3434"},"references":[{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/C36JLPHUPKDFAX6D5WYFC4ALO2K7RDUQ/"},{"type":"ADVISORY","url":"https://github.com/symfony/symfony/security/advisories/GHSA-mcx4-f5f5-4859"},{"type":"ADVISORY","url":"https://symfony.com/blog/cve-2020-5255-prevent-cache-poisoning-via-a-response-content-type-header"},{"type":"FIX","url":"https://github.com/symfony/symfony/commit/dca343442e6a954f96a2609e7b4e9c21ed6d74e6"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T15:13:45.945709Z"}}