CVE-2026-45067: ### Description `Symfony\Component\Mime\Address` is the value-object every Symfony Mailer address (to/cc/bcc/from/reply-to) flows through; its constructor is…

PriorityP339medium6.3CVSS 4.0

AVNACLATPPRNUINVCNVILVANSCNSINSANEXCRXIRXARXMAVXMACXMATXMPRXMUIXMVCXMVIXMVAXMSCXMSIXMSAXSXAUXRXVXREXUX

EPSS

0.62%

45.7th percentile

### 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

12 ranges

Vendor	Product	Version range	Fixed in
symfony	mime	>= 0 < 5.4.52	5.4.52
symfony	mime	>= 6.0.0 < 6.4.40	6.4.40
symfony	mime	>= 7.0.0 < 7.4.12	7.4.12
symfony	mime	>= 8.0.0 < 8.0.12	8.0.12
symfony	symfony	< 5.4.52	5.4.52
symfony	symfony	—	—
symfony	symfony	—	—
symfony	symfony	—	—
symfony	symfony	>= 0 < 5.4.52	5.4.52
symfony	symfony	>= 6.0.0 < 6.4.40	6.4.40
symfony	symfony	>= 7.0.0 < 7.4.12	7.4.12
symfony	symfony	>= 8.0.0 < 8.0.12	8.0.12

Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.