HighGHSA-qpmx-3rfj-7rhvCVE-2026-45067

Symfony has Email Header / SMTP Command Injection via CRLF in Symfony\Component\Mime\Address

Published 27 May 2026 · Updated 10 Sept 2026

Affected packages

symfony/mimeComposer
Affected
<5.4.52
Fixed in
5.4.52
Update to the fixed version for your release line, for example:composer require symfony/mime:^5.4.52
symfony/symfonyComposer
Affected
<5.4.52
Fixed in
5.4.52
Update to the fixed version for your release line, for example:composer require symfony/symfony:^5.4.52
symfony/mimeComposer
Affected
>=6.0.0 <6.4.40
Fixed in
6.4.40
Update to the fixed version for your release line, for example:composer require symfony/mime:^6.4.40
symfony/mimeComposer
Affected
>=7.0.0 <7.4.12
Fixed in
7.4.12
Update to the fixed version for your release line, for example:composer require symfony/mime:^7.4.12
symfony/mimeComposer
Affected
>=8.0.0 <8.0.12
Fixed in
8.0.12
Update to the fixed version for your release line, for example:composer require symfony/mime:^8.0.12
symfony/symfonyComposer
Affected
>=6.0.0 <6.4.40
Fixed in
6.4.40
Update to the fixed version for your release line, for example:composer require symfony/symfony:^6.4.40
symfony/symfonyComposer
Affected
>=7.0.0 <7.4.12
Fixed in
7.4.12
Update to the fixed version for your release line, for example:composer require symfony/symfony:^7.4.12
symfony/symfonyComposer
Affected
>=8.0.0 <8.0.12
Fixed in
8.0.12
Update to the fixed version for your release line, for example:composer require symfony/symfony:^8.0.12

Details

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.

Is GHSA-qpmx-3rfj-7rhv in any of your client repos?

Checking one package by hand is fine. Checking it across forty client projects is not. NPMscan reads the lockfiles in every GitHub repo you pick, finds each project with an affected symfony/mime, and gives you the command that fixes it.

Scan a project free, no signupOr connect GitHub to scan every repo

References

Advisory data from OSV.dev (opens OSV.dev in a new tab), refreshed daily.