SymfonyFramework / library · Sensiolabs
CVE-2018-11386
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 · uneditedAn issue was discovered in the HttpFoundation component in Symfony 2.7.x before 2.7.48, 2.8.x before 2.8.41, 3.3.x before 3.3.17, 3.4.x before 3.4.11, and 4.0.x before 4.0.11. The PDOSessionHandler class allows storing sessions on a PDO connection. Under some configurations and with a well-crafted payload, it was possible to do a denial of service on a Symfony application without too much resources.
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 vulnerability exists in Symfony's HttpFoundation PDOSessionHandler class, which handles session storage via PDO connections. Under certain configurations, a well-crafted session payload can trigger a denial of service attack with minimal resources. This affects Symfony versions 2.7.x before 2.7.48, 2.8.x before 2.8.41, 3.3.x before 3.3.17, 3.4.x before 3.4.11, and 4.0.x before 4.0.11.
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
>= 2.7.0, < 2.7.48>= 2.8.0, < 2.8.41>= 3.3.0, < 3.3.17>= 3.4.0, < 3.4.11>= 4.0.0, < 4.0.11
Debian LinuxOperating system
= 9.0CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/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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Determine installed Symfony versionLocate and inspect the Symfony version file or composer.lock/composer.json in your project. Common locations include vendor/composer/installed.json, composer.lock, or the Symfony VERSION file in the vendor/symfony/http-foundation directory.Affected if The installed version falls within any of these ranges: 2.7.0 to 2.7.47, 2.8.0 to 2.8.40, 3.3.0 to 3.3.16, 3.4.0 to 3.4.10, or 4.0.0 to 4.0.10.
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Identify session handler configurationExamine your Symfony application configuration files for session handler settings. Look for framework.session.handler_id or similar session configuration in your config files. Check if the PDOSessionHandler class is referenced.Affected if The session handler is configured to use Symfony\Component\HttpFoundation\Session\Storage\Handler\PdoSessionHandler or a custom PDO-based session handler.
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Verify PDO connection settingsIf PdoSessionHandler is in use, review the PDO DSN and options configured for the session handler. Check your services configuration or parameters files for pdo.db_options, pdo.dsn, or similar PDO-related session storage parameters.Affected if A PDO connection is configured for session storage, particularly with MySQL or PostgreSQL drivers.
You are affected if your Symfony version is within the vulnerable ranges AND you are using the PDO session handler for session storage.
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.
From vendor data2.7.482.8.413.3.17
Upgrade Symfony to version 2.7.48, 2.8.41, 3.3.17, 3.4.11, 4.0.11 or later to receive the patch. If immediate upgrade is not feasible, review and restrict PDO session handler configurations or implement rate limiting as a compensating control.
Fix this in Symfony
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 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 $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-11386 — 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-2018-11386 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
- No weaponised exploit code, or anything meant to cause harm
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