SymfonyFramework / library · Sensiolabs
CVE-2019-18888
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 Symfony 2.8.0 through 2.8.50, 3.4.0 through 3.4.34, 4.2.0 through 4.2.11, and 4.3.0 through 4.3.7. If an application passes unvalidated user input as the file for which MIME type validation should occur, then arbitrary arguments are passed to the underlying file command. This is related to symfony/http-foundation (and symfony/mime in 4.3.x).
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 confidenceCommand injection vulnerability in Symfony's MIME type validation (symfony/http-foundation and symfony/mime components). If an application passes unvalidated user input as the file path for MIME type validation, an attacker can inject arbitrary arguments to the underlying `file` command, potentially achieving remote code execution.
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, <= 2.8.50>= 3.4.0, <= 3.4.34>= 4.2.0, <= 4.2.11>= 4.3.0, <= 4.3.7
FedoraOperating system
= 30= 31CVSS 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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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.
-
Check installed Symfony versionRun `composer show symfony/http-foundation` or `composer show symfony/mime` to see the installed version, or check your composer.lock file for the version numberAffected if The version is 2.8.0-2.8.50, 3.4.0-3.4.34, 4.2.0-4.2.11, or 4.3.0-4.3.7
-
Identify MIME type validation usageSearch your codebase for calls to MimeTypeExtensionGuesser, MimeTypeFileBinaryGuesser, or the `file` command being invoked through Symfony's mime components. Look for patterns like `$guesser->guess()` with user-controlled inputAffected if Your application uses Symfony's MIME type guessers with file paths derived from user input
-
Verify user input reaches MIME validationAudit your application code that handles file uploads or accepts file paths from users. Trace whether $_GET, $_POST, or request parameters flow into any Symfony mime guessing functions such as guessExtension(), guess(), or FileBinary MIME type detectionAffected if User-supplied file paths are passed directly to Symfony's MIME type detection without validation
-
Check for command injection entry pointsReview any code that constructs shell commands using user input, specifically related to file type detection. Look for string concatenation or interpolation of user variables into commands that invoke the `file` binaryAffected if User input is concatenated with commands that invoke the system `file` command through Symfony's mime components
You are affected if your Symfony version is within the affected ranges AND your application passes unvalidated user-provided file paths to Symfony's MIME type guessing functions.
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 dataUpgrade to Symfony versions 2.8.51+, 3.4.35+, 4.2.12+, or 4.3.8+. Additionally, validate and sanitize all user-supplied file paths before passing them to MIME type validation functions.
Fix this in Symfony
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-18888 — 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-2019-18888 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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