Vulnerability · Published Jul 14, 2026 · Assigned by GitHub_M
CVE-2026-45067Symfony: Email Header / SMTP Command Injection via CRLF in Symfony\Component\Mime\Address
Medium 6.3
In plain English
A medium-severity security flaw in symfony from symfony. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official 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 & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | symfony | 5.4.53+dfsg-0+deb12u1 | DEBIAN-CVE-2026-45067 |
| Debian:13 | symfony | 6.4.41+dfsg-0+deb13u1 | DEBIAN-CVE-2026-45067 |
| Debian:14 | symfony | 7.4.12+dfsg-1 | DEBIAN-CVE-2026-45067 |
| Packagist | symfony/mime | 5.4.52 | GHSA-qpmx-3rfj-7rhv |
| Packagist | symfony/mime | 8.0.12 | GHSA-qpmx-3rfj-7rhv |
| Packagist | symfony/mime | 6.4.40 | GHSA-qpmx-3rfj-7rhv |
| Packagist | symfony/mime | 7.4.12 | GHSA-qpmx-3rfj-7rhv |
| Packagist | symfony/symfony | 8.0.12 | GHSA-qpmx-3rfj-7rhv |
| Packagist | symfony/symfony | 5.4.52 | GHSA-qpmx-3rfj-7rhv |
| Packagist | symfony/symfony | 6.4.40 | GHSA-qpmx-3rfj-7rhv |
| Packagist | symfony/symfony | 7.4.12 | GHSA-qpmx-3rfj-7rhv |
| Ubuntu:25.10 | symfony | no fix listed | UBUNTU-CVE-2026-45067 |
| Ubuntu:26.04:LTS | symfony | no fix listed | UBUNTU-CVE-2026-45067 |
| Ubuntu:26.10 | symfony | no fix listed | UBUNTU-CVE-2026-45067 |
Affected products (as reported)
Weakness: CWE-93 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
References
- https://github.com/symfony/symfony/security/advisories/GHSA-qpmx-3rfj-7rhv x_refsource_CONFIRM
- https://github.com/symfony/symfony/commit/a1c42cbe517bc146a54da7505a107ded317478fe x_refsource_MISC
- https://github.com/symfony/symfony/releases/tag/v5.4.52 x_refsource_MISC
- https://github.com/symfony/symfony/releases/tag/v6.4.40 x_refsource_MISC
- https://github.com/symfony/symfony/releases/tag/v7.4.12 x_refsource_MISC
- https://github.com/symfony/symfony/releases/tag/v8.0.12 x_refsource_MISC