SymfonyFramework / library · Sensiolabs
CVE-2026-45754
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedSymfony 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe Mailjet mailer bridge and LOX24 notifier bridge in Symfony receive webhook secrets in their configuration but fail to perform any signature verification on incoming webhook payloads, allowing unauthenticated attackers to send forged event data via POST requests.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
SymfonyFramework / library
>= 6.4.0, < 6.4.40>= 7.0.0, < 7.4.12>= 8.0.0, < 8.0.12CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Determine installed Symfony versionRun `composer show symfony/framework-bundle 2>/dev/null | grep versions` or check your composer.lock for the symfony/* packages versionAffected if Version is >= 6.4.0 and < 6.4.40, OR >= 7.0.0 and < 7.4.12, OR >= 8.0.0 and < 8.0.12
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Check for Mailjet mailer bridge usageRun `composer show | grep -i mailjet` or search for 'mailjet' in your composer.json and config filesAffected if The Mailjet mailer bridge package is installed and configured
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Check for LOX24 notifier bridge usageRun `composer show | grep -i lox24` or search for 'lox24' in your composer.json and config filesAffected if The LOX24 notifier bridge package is installed and configured
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Inspect webhook configuration for affected bridgesCheck your Symfony configuration files (.yaml or .php in config/packages/) for any mailer_dsn or notifier_dsn using mailjet or lox24, and verify if a webhook_secret parameter is definedAffected if Either bridge is configured with a webhook_secret but signature validation is not being performed (the vulnerability exists when secrets are present but unused)
You are affected if your Symfony version falls within the vulnerable ranges AND you have either the Mailjet mailer bridge or LOX24 notifier bridge installed with webhook secrets configured.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped6.4.407.4.128.0.12
Upgrade Symfony to versions 6.4.40, 7.4.12, or 8.0.12 which implement proper webhook signature validation.
6.4.40 (for 6.4.x) or 7.4.12 (for 7.x) or 8.0.12 (for 8.0.x)
- Identify the current Symfony version by running 'composer show symfony/symfony' or inspecting your composer.lock file
- For Symfony 6.4.x (versions 6.4.0 to 6.4.39): Run 'composer require symfony/symfony:6.4.40 --no-interaction' to upgrade to the fixed version
- For Symfony 7.0.x to 7.4.x (versions 7.0.0 to 7.4.11): Run 'composer require symfony/symfony:7.4.12 --no-interaction' to upgrade to the fixed version
- For Symfony 8.0.x (versions 8.0.0 to 8.0.11): Run 'composer require symfony/symfony:8.0.12 --no-interaction' to upgrade to the fixed version
- Run 'composer update symfony/symfony' to apply the changes
- Clear the Symfony cache with 'php bin/console cache:clear'
- Test the application thoroughly, specifically verifying Mailjet mailer bridge and LOX24 notifier webhook functionality
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Symfony
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-45754 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-45754 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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