CVE-2026-45754 in Symfony Mailer and Notifier Bridges
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 6.4.40, 7.4.12, and 8.0.12, the Mailjet mailer bridge and LOX24 notifier bridge webhook parsers received configured webhook secrets but did not verify them, allowing unauthenticated POST requests to inject forged Mailjet and LOX24 event payloads. This issue is fixed in versions 6.4.40, 7.4.12, and 8.0.12.
Quick answer
Symfony should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- Symfony before 6.4.40
- Symfony before 7.4.12
- Symfony before 8.0.12
Fixed versions
- 6.4.40
- 7.4.12
- 8.0.12
How to fix it
CVE-2026-45754 is a authentication bypass issue in Symfony. Update from Symfony before 6.4.40 to 6.4.40 or newer. Keep it simple: upgrade first, then test the normal user flow.
- Find every place where Symfony is installed or used.
- Upgrade Symfony to 6.4.40 or a newer fixed release from the vendor.
- If you cannot upgrade right away, limit access to the affected feature until the update is done.
- Restart or redeploy the service if the product needs it after the update.
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Verify the fix
- Confirm the installed version is 6.4.40 or newer.
- Run a normal login, admin, and user flow to make sure the site still works.
- Check logs for new errors after the update.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-45754?
Symfony versions listed as affected should be reviewed: Symfony before 6.4.40, Symfony before 7.4.12, Symfony before 8.0.12.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.