CVE-2026-45067: medium-severity vulnerability in symfony
Symfony: Email Header / SMTP Command Injection via CRLF in Symfony\Component\Mime\Address
Published
33Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 6.3epss 0.6%
from disclosure to weapon0 days
Published on NVDJul 14
1st PoCJun 9
exploitation probability
0.6%top 52% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
### 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.
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
Affected products
symfony · symfonypublic PoCs found — 1
githubgithub.com/HORKimhab/CVE-2026-45067★ 0⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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References
https://github.com/symfony/symfony/commit/a1c42cbe517bc146a54da7505a107ded317478fehttps://github.com/symfony/symfony/releases/tag/v5.4.52https://github.com/symfony/symfony/releases/tag/v6.4.40https://github.com/symfony/symfony/releases/tag/v7.4.12https://github.com/symfony/symfony/releases/tag/v8.0.12https://github.com/symfony/symfony/security/advisories/GHSA-qpmx-3rfj-7rhv