CVE-2026-45067: Symfony Mime CRLF injection in Address constructor

CVE-2026-45067 · Severity: high · CVSS 4 · Published 2026-07-14

A vulnerability exists in the Symfony Mailer component, a popular tool used by PHP applications to send emails. The software fails to properly block line breaks in email addresses, which could allow an attacker to inject malicious commands or headers into outgoing emails. This could lead to unauthorized emails being sent or the manipulation of email content, potentially damaging a company's reputation or facilitating phishing attacks.

Technologies: symfony/mime (Packagist), symfony/symfony (Packagist), Symfony Mime. Vendors: Packagist, Symfony.

Quick answers

Is CVE-2026-45067 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-45067 being exploited in the wild.
How severe is CVE-2026-45067?
High severity, with a CVSS score of 4, published 14 July 2026.
Which products and versions are affected?
symfony/mime (Packagist) ECOSYSTEM:introduced=0,fixed=5.4.52; symfony/symfony (Packagist) ECOSYSTEM:introduced=0,fixed=5.4.52; Symfony Mime < 5.4.52, >= 6.0.0 < 6.4.40, >= 7.0.0 < 7.4.12, >= 8.0.0 < 8.0.12.
Is there a fix for CVE-2026-45067?
Yes. symfony/mime (Packagist): upgrade to 5.4.52 or later; symfony/symfony (Packagist): upgrade to 5.4.52 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-45067 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-45067?
Check whether you run symfony/mime (Packagist), symfony/symfony (Packagist) or Symfony Mime at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • symfony/mime (Packagist): upgrade to 5.4.52 or later
    composer require symfony/mime:^5.4.52
  • symfony/symfony (Packagist): upgrade to 5.4.52 or later
    composer require symfony/symfony:^5.4.52

Technical details

A CRLF injection vulnerability (CWE-93) exists in the `Symfony\Component\Mime\Address` constructor. The component fails to neutralize line breaks (\r\n) when they are contained within a quoted string in the local-part of an email address. Because this component is treated as a security boundary for mailer addresses (To, CC, BCC, etc.), an attacker can provide a crafted email address that, when rendered into message headers or used in SMTP transport protocol lines (MAIL FROM/RCPT TO), injects new headers or SMTP commands. This can be exploited to add unauthorized recipients or modify email metadata. The issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12 by rejecting addresses containing control characters.

Affected products

  • Symfony symfony/symfony < 5.4.52, >= 6.0.0-BETA1, < 6.4.40, >= 7.0.0-BETA1, < 7.4.12, >= 8.0.0-BETA1, < 8.0.12

Identifiers

  • CVE-2026-45067
  • GHSA-qpmx-3rfj-7rhv

Timeline

  • 2026-05-20: patched: Fixed versions released across multiple branches.
  • 2026-07-14: advisory: Security advisory published.

References

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