Cloudanix VulnDB

CVE-2026-45070

Medium · 6.5

Symfony has Email Header Injection via Non-Token Characters in Mime Parameter Names

CVSS

6.5

EPSS

0.4%

Published

May 27, 2026

CISA due date

—

The record

`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"`). RFC 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. A 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.

Affected packages

Ecosystem Package Introduced Fixed

Related vulnerabilities