{"id":"CVE-2026-45070","aliases":["GHSA-vqc8-7275-q272"],"url":"https://o3.security/vulnerability/CVE-2026-45070","summary":"Symfony: Email Header Injection via Non-Token Characters in Mime Parameter Names","details":"### Description\n\n`Symfony\\Component\\Mime\\Header\\ParameterizedHeader` (and the related parameter handling reachable from `Symfony\\Component\\Mime\\Header\\Headers`) is responsible for serializing structured headers such as `Content-Type` and `Content-Disposition`, which carry `key=value` parameters (e.g. `Content-Disposition: attachment; filename=\"x\"`).\n\nRFC 2045 / RFC 5322 require parameter *names* to be `tokens`: a restricted ASCII subset that excludes whitespace, CR/LF, and the `tspecials` set. Symfony's parameter handling validates and properly encodes parameter *values*, but does not validate parameter *names*: the supplied name is emitted verbatim into the serialized header.\n\nA caller that derives a parameter name from untrusted input, e.g. an application that lets a user influence a `Content-Disposition` parameter name, can include `\\r\\n` or other non-token bytes inside the name, terminating the current header and injecting additional headers in the rendered message. This is the classic CRLF / header-injection primitive applied to the parameter-name slot.\n\n### Resolution\n\n`ParameterizedHeader` now rejects parameter names that contain bytes outside the RFC `token` character class.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e62ea217f8b4ca8ae922ad0f949e0c4dc1f9b613) for branch 5.4.\n\n### Credits\n\nSymfony would like to thank Fabian Fleischer for reporting the issue and Alexandre Daubois for fixing it.","published":"2026-07-14T18:25:46.647Z","modified":"2026-08-12T03:51:32.387478551Z","cvss":null,"epss":{"score":0.00292,"percentile":0.21824,"asOf":"2026-08-16"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"symfony/mime","fixedVersion":"5.4.52"},{"ecosystem":"Packagist","name":"symfony/symfony","fixedVersion":"5.4.52"},{"ecosystem":"Packagist","name":"symfony/mime","fixedVersion":"6.4.40"},{"ecosystem":"Packagist","name":"symfony/mime","fixedVersion":"7.4.12"},{"ecosystem":"Packagist","name":"symfony/mime","fixedVersion":"8.0.12"},{"ecosystem":"Packagist","name":"symfony/symfony","fixedVersion":"6.4.40"},{"ecosystem":"Packagist","name":"symfony/symfony","fixedVersion":"7.4.12"},{"ecosystem":"Packagist","name":"symfony/symfony","fixedVersion":"8.0.12"}],"fix":{"url":"https://github.com/symfony/symfony/commit/e62ea217f8b4ca8ae922ad0f949e0c4dc1f9b613","label":"symfony/symfony@e62ea21"},"references":[{"type":"WEB","url":"https://github.com/symfony/symfony/releases/tag/v5.4.52"},{"type":"WEB","url":"https://github.com/symfony/symfony/releases/tag/v6.4.40"},{"type":"WEB","url":"https://github.com/symfony/symfony/releases/tag/v7.4.12"},{"type":"WEB","url":"https://github.com/symfony/symfony/releases/tag/v8.0.12"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45070.json"},{"type":"ADVISORY","url":"https://github.com/symfony/symfony/security/advisories/GHSA-vqc8-7275-q272"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45070"},{"type":"FIX","url":"https://github.com/symfony/symfony/commit/e62ea217f8b4ca8ae922ad0f949e0c4dc1f9b613"},{"type":"WEB","url":"https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/mime/CVE-2026-45070.yaml"},{"type":"WEB","url":"https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45070.yaml"},{"type":"PACKAGE","url":"https://github.com/symfony/symfony"},{"type":"WEB","url":"https://symfony.com/cve-2026-45070"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:32.387478551Z"}}