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Fencer Vulns
medium 6.3

CVE-2026-45067 json

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

published 2026-05-27 5 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-44322 , GHSA-qpmx-3rfj-7rhv

cvss
6.3
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

### 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.

Patch / fix

  • packagist symfony/mime 5.4.52, 6.4.40, 7.4.12, 8.0.12
  • packagist symfony/symfony 5.4.52, 6.4.40, 7.4.12, 8.0.12
  • sensiolabs symfony 5.4.52, 6.4.40, 7.4.12, 8.0.12
  • sensiolabs twig 5.4.52, 6.4.40, 7.4.12, 8.0.12
  • symfony Debian 12 5.4.53+dfsg-0+deb12u1
  • symfony Debian 13 6.4.41+dfsg-0+deb13u1
  • symfony Debian 14 7.4.12+dfsg-1

debian advisories DEBIAN-CVE-2026-45067

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.60% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.3 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
CNA 4.0 6.3 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
packagist 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
packagist 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

Affected products

  • symfony symfony

Classification

Weakness
  • CWE-93 Improper Neutralization of CRLF Sequences

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.