What is CVE-2026-45068?

CVE-2026-45068 is a medium-severity security vulnerability in symfony/mailer (composer), affecting versions < 5.4.52. It is fixed in 5.4.52, 6.4.40, 7.4.12, 8.0.12.

Which packages are affected by CVE-2026-45068?

symfony/mailer (composer) versions < 5.4.52; symfony/symfony (composer) versions < 5.4.52.

Is there a fix for CVE-2026-45068?

Yes. CVE-2026-45068 is fixed in 5.4.52, 6.4.40, 7.4.12, 8.0.12. Upgrade to this version or later.

Is CVE-2026-45068 exploitable, and should I be worried?

Whether CVE-2026-45068 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2026-45068 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

CVE-2026-45068 in symfony/mailer

Q: Which packages are affected by CVE-2026-45068?

symfony/mailer (composer) versions < 5.4.52; symfony/symfony (composer) versions < 5.4.52.

Q: Is there a fix for CVE-2026-45068?

Yes. CVE-2026-45068 is fixed in 5.4.52, 6.4.40, 7.4.12, 8.0.12. Upgrade to this version or later.

Q: Is CVE-2026-45068 exploitable, and should I be worried?

Whether CVE-2026-45068 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2026-45068 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2026-45068?

Upgrade: symfony/mailer to 5.4.52 or later, symfony/symfony to 5.4.52 or later, symfony/mailer to 6.4.40 or later, symfony/mailer to 7.4.12 or later, symfony/mailer to 8.0.12 or later, symfony/symfony to 6.4.40 or later, symfony/symfony to 7.4.12 or later, symfony/symfony to 8.0.12 or later.

Summary

Symfony has an Argument Injection in SendmailTransport via Dash-Prefixed Recipient Address

Description

Symfony Mailer selects a transport via the MAILER_DSN environment variable / configuration (e.g. smtp://..., sendmail://..., native://default). SendmailTransport invokes the local sendmail binary and supports two modes: -bs (speak SMTP over stdin: the default) and -t (read the message on stdin, pass recipients as command-line arguments).

In -t mode, recipient addresses are appended to the sendmail command line without a -- end-of-options separator. A recipient address beginning with - (which Symfony\Component\Mime\Address accepts as valid) is therefore interpreted by sendmail as a command-line option rather than an address.

Resolution

The SendmailTransport transport now ensure -- is set before the list of recipients.

The patch for this issue is available here for branch 5.4.

Credits

Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

Impact

Affected versions

symfony/mailer (< 5.4.52) symfony/symfony (< 5.4.52) symfony/mailer (>= 6.0.0, < 6.4.40) symfony/mailer (>= 7.0.0, < 7.4.12) symfony/mailer (>= 8.0.0, < 8.0.12) symfony/symfony (>= 6.0.0, < 6.4.40) symfony/symfony (>= 7.0.0, < 7.4.12) symfony/symfony (>= 8.0.0, < 8.0.12)

Security releases

symfony/mailer → 5.4.52 (composer) symfony/symfony → 5.4.52 (composer) symfony/mailer → 6.4.40 (composer) symfony/mailer → 7.4.12 (composer) symfony/mailer → 8.0.12 (composer) symfony/symfony → 6.4.40 (composer) symfony/symfony → 7.4.12 (composer) symfony/symfony → 8.0.12 (composer)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade the following packages to resolve this vulnerability:

symfony/mailer to 5.4.52 or later; symfony/symfony to 5.4.52 or later; symfony/mailer to 6.4.40 or later; symfony/mailer to 7.4.12 or later; symfony/mailer to 8.0.12 or later; symfony/symfony to 6.4.40 or later; symfony/symfony to 7.4.12 or later; symfony/symfony to 8.0.12 or later

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2026-45068? CVE-2026-45068 is a medium-severity security vulnerability in symfony/mailer (composer), affecting versions < 5.4.52. It is fixed in 5.4.52, 6.4.40, 7.4.12, 8.0.12.
Which packages are affected by CVE-2026-45068?
- symfony/mailer (composer) (versions < 5.4.52)
- symfony/symfony (composer) (versions < 5.4.52)
Is there a fix for CVE-2026-45068? Yes. CVE-2026-45068 is fixed in 5.4.52, 6.4.40, 7.4.12, 8.0.12. Upgrade to this version or later.
Is CVE-2026-45068 exploitable, and should I be worried? Whether CVE-2026-45068 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2026-45068 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2026-45068?
- Upgrade symfony/mailer to 5.4.52 or later
- Upgrade symfony/symfony to 5.4.52 or later
- Upgrade symfony/mailer to 6.4.40 or later
- Upgrade symfony/mailer to 7.4.12 or later
- Upgrade symfony/mailer to 8.0.12 or later
- Upgrade symfony/symfony to 6.4.40 or later
- Upgrade symfony/symfony to 7.4.12 or later
- Upgrade symfony/symfony to 8.0.12 or later