HOMEVULNERABILITIESCVE-2018-6334
CRITICAL

CVE-2018-6334

CWE-621Published: December 31, 2018· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

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).

NVD Source

Technical Analysis

CVE-2018-6334 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

facebook1 product(s)
hhvm
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/facebook/hhvm/commit/6937de5544c3eead3466b75020d8382080ed0cff
PATCHhttps://hhvm.com/blog/2018/03/30/hhvm-3.25.2.html
PATCHhttps://github.com/facebook/hhvm/commit/6937de5544c3eead3466b75020d8382080ed0cff
PATCHhttps://hhvm.com/blog/2018/03/30/hhvm-3.25.2.html

All References (4)

→
https://github.com/facebook/hhvm/commit/6937de5544c3eead3466b75020d8382080ed0cffPatch · Third Party Advisory
→
https://hhvm.com/blog/2018/03/30/hhvm-3.25.2.htmlPatch · Third Party Advisory
→
https://github.com/facebook/hhvm/commit/6937de5544c3eead3466b75020d8382080ed0cffPatch · Third Party Advisory
→
https://hhvm.com/blog/2018/03/30/hhvm-3.25.2.htmlPatch · Third Party Advisory

Quick Facts

CVE IDCVE-2018-6334
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-621
CISA KEVNo
Affected1 vendor(s)
PublishedDec 31, 2018

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2018-6334 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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