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SymfonyFramework / library · Sensiolabs

CVE-2019-18889

CRITICAL · 9.8 CVSS v3.1 Published 2019-11-21
Fix available
A fix is available. Upgrade to after 4.3.7 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
An issue was discovered in Symfony 3.4.0 through 3.4.34, 4.2.0 through 4.2.11, and 4.3.0 through 4.3.7. Serializing certain cache adapter interfaces could result in remote code injection. This is related to symfony/cache.

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 confidence

Insecure deserialization in Symfony's cache component allows remote code injection through certain cache adapter interfaces. Attackers can serialize malicious objects that, when deserialized, execute arbitrary code on the server.

MitigationUpgrade Symfony to version 3.4.35, 4.2.12, 4.3.8 or later to patch the vulnerable cache serialization. Alternatively, avoid serializing cache adapter interface objects.

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
Affected:>= 3.4.0, <= 3.4.34>= 4.2.0, <= 4.2.11>= 4.3.0, <= 4.3.7
FedoraOperating system
Affected:= 31

CVSS 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:3.1/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Symfony version
    Run 'composer show symfony/symfony 2>/dev/null | grep -i version' or check the version constant in vendor/symfony/symfony/src/Symfony/Component/HttpKernel/Kernel.php
    Affected if Version is 3.4.0 to 3.4.34, 4.2.0 to 4.2.11, or 4.3.0 to 4.3.7
  2. Confirm cache component is present
    Run 'composer show symfony/cache 2>/dev/null' or verify vendor/symfony/cache directory exists
    Affected if The Symfony cache component is installed
  3. Identify cache adapter configuration
    Search for cache configuration in app/config/packages/cache.yaml or config/packages/cache.yaml, or look for CacheInterface usage in the codebase
    Affected if Cache adapters that serialize interface objects are configured and in use
  4. Check for unsafe serialized data in cache storage
    Inspect cache storage (Redis, Memcached, database, or file-based cache) for serialized objects that may contain injected malicious payloads
    Affected if Untrusted serialized data can be written to or already exists in the cache storage backend

You are affected if your Symfony version falls within the vulnerable ranges AND your application uses the Symfony cache component with adapters that serialize cache adapter interface objects.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to a release after 4.3.7
Interim mitigation

Upgrade Symfony to version 3.4.35, 4.2.12, 4.3.8 or later to patch the vulnerable cache serialization. Alternatively, avoid serializing cache adapter interface objects.

Recommended fix High confidence

Upgrade to Symfony 3.4.35+, 4.2.12+, or 4.3.8+ (or the latest 4.4 LTS which contains the fix)

  1. Identify all projects using the vulnerable Symfony versions (3.4.0-3.4.34, 4.2.0-4.2.11, 4.3.0-4.3.7)
  2. Update the symfony/cache dependency to the fixed version
  3. For Symfony 3.4.x: upgrade to 3.4.35 or later
  4. For Symfony 4.2.x: upgrade to 4.2.12 or later
  5. For Symfony 4.3.x: upgrade to 4.3.8 or later
  6. Run tests to verify the upgrade does not break existing functionality
  7. Deploy the updated application
Caveat Patch releases (x.y.z where z is the patch number) typically have no breaking changes; however, test thoroughly before deploying to production

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Symfony Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-18889 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data