SymfonyFramework / library · Sensiolabs
CVE-2016-2403
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 before 2.8.6 and 3.x before 3.0.6 allows remote attackers to bypass authentication by logging in with an empty password and valid username, which triggers an unauthenticated bind.
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 confidenceThis is an authentication bypass vulnerability in Symfony's LDAP authentication component. Attackers can bypass authentication by supplying a valid username with an empty password, which triggers an unauthenticated LDAP bind that succeeds against misconfigured LDAP directories.
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
= 2.8.0= 2.8.1= 2.8.2= 2.8.3= 2.8.4= 2.8.5= 3.0.0= 3.0.1= 3.0.2= 3.0.3= 3.0.4= 3.0.5CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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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Check Symfony framework versionRun `composer show symfony/symfony | grep version` or inspect your composer.lock file for the installed symfony/symfony versionAffected if The installed version is 2.8.0-2.8.5 or 3.0.0-3.0.5
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Verify LDAP authentication is enabledInspect your Symfony security configuration file (typically security.yml or security.yaml in config/packages/) and look for a firewall provider using ldap as the authentication providerAffected if LDAP authentication is configured and the Symfony version is in the affected range
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Identify the LDAP provider configurationLocate the LDAP provider definition in the security configuration file under the providers section and identify the service ID used for LDAP (such as ldap)}Affected if An LDAP provider is defined in the security configuration
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Inspect LDAP bind configurationReview the LDAP connection and bind settings in your Symfony parameters.yml, parameters.yml.dist, or any custom LDAP configuration files to determine if empty passwords or unauthenticated binds are permittedAffected if The LDAP configuration allows empty passwords or does not explicitly reject unauthenticated binds
You are affected if your Symfony version is 2.8.0-2.8.5 or 3.0.0-3.0.5, you use LDAP authentication, and your LDAP directory accepts unauthenticated binds or empty password attempts.
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 · scopedUpgrade Symfony to version 2.8.6, 3.0.6, or later. As a temporary workaround, configure the LDAP provider to reject empty passwords and disable unauthenticated binds.
Symfony 2.8.6 or later (or Symfony 3.0.6 or later)
- 1. Back up your application codebase and database before making any changes
- 2. Update your Composer dependencies to upgrade Symfony: run `composer require symfony/symfony:"^2.8.6"` or `composer require symfony/symfony:"^3.0.6"` depending on your major version
- 3. Alternatively, manually edit your composer.json to set the Symfony version constraint to ^2.8.6 or ^3.0.6 and run `composer update symfony/symfony`
- 4. Clear the Symfony cache after upgrade: `php bin/console cache:clear` (or `app/console cache:clear` for older setups)
- 5. Test your application's authentication functionality thoroughly to confirm the fix works and no regressions were introduced
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Symfony
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-2403 — 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-2016-2403 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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- Version or environment caveats, and links to real fixes
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