Symfony has Email Header / SMTP Command Injection via CRLF in Symfony\Component\Mime\Address
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 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 software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | symfony/mime | < 5.4.52, >= 6.0.0, < 6.4.40, >= 7.0.0, < 7.4.12, >= 8.0.0, < 8.0.12 | 5.4.52, 6.4.40, 7.4.12, 8.0.12 |
| Composer package | symfony/symfony | < 5.4.52, >= 6.0.0, < 6.4.40, >= 7.0.0, < 7.4.12, >= 8.0.0, < 8.0.12 | 5.4.52, 6.4.40, 7.4.12, 8.0.12 |
References
- https://github.com/symfony/symfony/security/advisories/GHSA-qpmx-3rfj-7rhv
- https://github.com/symfony/symfony/commit/dc2dbd29211eb4ddc451373fa1374fb926e94604
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/mime/CVE-2026-45067.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45067.yaml
- https://github.com/symfony/symfony
- https://symfony.com/cve-2026-45067
- CVSS vector
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- Weakness (CWE)
CWE-93- Platform
- Composer
- Package
symfony/mime, symfony/symfony- Disclosed
- 27.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-qpmx-3rfj-7rhv - CC BY 4.0
Vulnerability history: symfony/mime
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 12.2019 05.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
- Medium 1
Disclosures per year
- 2019: 1
- 2020: 0
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 2
-
Symfony has Email Header / SMTP Command Injection via CRLF in Symfony\Component\Mime\Address this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.