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GHSA-qpmx-3rfj-7rhv

Symfony has Email Header / SMTP Command Injection via CRLF in Symfony\Component\Mime\Address

Source: GitHub Advisory Database (reviewed) High CVE-2026-45067

Packages

EcosystemPackageAffectedFixed in
Packagist symfony/mime < 5.4.52 5.4.52
Packagist symfony/symfony < 5.4.52 5.4.52
Packagist symfony/mime >= 6.0.0, < 6.4.40 6.4.40
Packagist symfony/mime >= 7.0.0, < 7.4.12 7.4.12
Packagist symfony/mime >= 8.0.0, < 8.0.12 8.0.12
Packagist symfony/symfony >= 6.0.0, < 6.4.40 6.4.40
Packagist symfony/symfony >= 7.0.0, < 7.4.12 7.4.12
Packagist symfony/symfony >= 8.0.0, < 8.0.12 8.0.12

Details

As written in the advisory (Markdown source, shown as plain text).

### Description `Symfony\Component\Mime\Address` is the value-object every Symfony Mailer address (to/cc/bcc/from/reply-to) flows through; its constructor is documented as validating the address and throwing on invalid input, so developers treat it as a security boundary. The constructor accepts email addresses whose local-part (the part before `@`) is an RFC-5322 *quoted string* containing raw `\r\n` bytes, e.g. `"x\r\nBcc: attacker@evil"@example.com`. The stored address is later emitted verbatim into (1) the rendered message headers and (2) `SmtpTransport`'s `MAIL FROM:<...>` / `RCPT TO:<...>` protocol lines, turning the embedded CRLF into a new mail header and/or a new SMTP command. ### Resolution The `Address` constructor now rejects addresses containing line breaks. The patch for this issue is available [here](https://github.com/symfony/symfony/commit/dc2dbd29211eb4ddc451373fa1374fb926e94604) for branch 5.4. ### Credits We would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

References

External links from the advisory. They lead to third-party sites.