CVE-2026-45067
Symfony has Email Header / SMTP Command Injection via CRLF in Symfony\Component\Mime\Address
Description
### 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.
Affected packages (3)
- Debian/symfonyfrom 0
- Packagist/symfony/mimefrom 0, < 5.4.52
- Packagist/symfony/symfonyfrom 0, < 5.4.52
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N |
References (7)
- ADVISORYhttps://security-tracker.debian.org/tracker/CVE-2026-45067
- PATCHhttps://github.com/symfony/symfony
- WEBhttps://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/mime/CVE-2026-45067.yaml
- WEBhttps://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45067.yaml
- WEBhttps://github.com/symfony/symfony/commit/dc2dbd29211eb4ddc451373fa1374fb926e94604
- WEBhttps://github.com/symfony/symfony/security/advisories/GHSA-qpmx-3rfj-7rhv
- WEBhttps://symfony.com/cve-2026-45067