HhvmApplication · Facebook

CVE-2018-6334

CRITICAL · 9.8 CVSS v3.1 Published 2018-12-31
Fix available
A fix is available. Upgrade to after 3.25.1 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

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
Multipart-file uploads call variables to be improperly registered in the global scope. In cases where variables are not declared explicitly before being used this can lead to unexpected behavior. This affects all supported versions of HHVM prior to the patch (3.25.1, 3.24.5, and 3.21.9 and below).

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

A detailed technical summary for this CVE is being prepared.

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
HhvmApplication
Affected:<= 3.21.9>= 3.21.10, <= 3.24.5>= 3.24.6, <= 3.25.1

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

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 3.25.1
Vendor patch github.com →
Recommended fix High confidence

HHVM 3.25.2 or latest stable 3.25.x release

  1. Identify the current HHVM version in use using `hhvm --version`
  2. Review the multipart file upload handling code in your application for variables that may be extracted from upload arrays without prior declaration
  3. Upgrade HHVM to version 3.25.2 or later (or the latest stable version available)
  4. After upgrading, verify that multipart file uploads work correctly and test that variables are not being improperly registered in global scope
  5. If using older major versions, upgrade to the latest stable release in that branch (3.21.x should upgrade to 3.21.10+, 3.24.x to 3.24.7+, or preferably the 3.25.x branch)
Caveat Review PHP/HHVM compatibility as HHVM version upgrades may introduce subtle behavioral changes; ensure application is tested thoroughly

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

We can identify the exact fixed release, upgrade, and verify it in staging — typical engagement from $2,300. Get the upgrade done

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2018-6334 — 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 sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2018-6334 in production — separate from our analysis above.

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.

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