CVE-2026-45067
Severity CVSS v4.0:
MEDIUM
Type:
CWE-93
Improper Neutralization of CRLF Sequences ('CRLF Injection')
Publication date:
14/07/2026
Last modified:
14/07/2026
Description
### Description<br />
<br />
`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.<br />
<br />
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`&#39;s `MAIL FROM:` / `RCPT TO:` protocol lines, turning the embedded CRLF into a new mail header and/or a new SMTP command.<br />
<br />
### Resolution<br />
<br />
The `Address` constructor now rejects addresses containing line breaks.<br />
<br />
The patch for this issue is available [here](https://github.com/symfony/symfony/commit/dc2dbd29211eb4ddc451373fa1374fb926e94604) for branch 5.4.<br />
<br />
### Credits<br />
<br />
We would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.
Impact
Base Score 4.0
6.30
Severity 4.0
MEDIUM
References to Advisories, Solutions, and Tools
- https://github.com/symfony/symfony/commit/a1c42cbe517bc146a54da7505a107ded317478fe
- https://github.com/symfony/symfony/releases/tag/v5.4.52
- https://github.com/symfony/symfony/releases/tag/v6.4.40
- https://github.com/symfony/symfony/releases/tag/v7.4.12
- https://github.com/symfony/symfony/releases/tag/v8.0.12
- https://github.com/symfony/symfony/security/advisories/GHSA-qpmx-3rfj-7rhv