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CVE-2018-6334: Facebook Hhvm: Arbitrary file upload

CVE-2018-6334 is rated critical with a CVSS v3.0 base score of 9.8 and affects Facebook Hhvm. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.

Vulnerability 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).

Severity breakdown

CVSS v3.0 9.8: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: None. No account or prior access is needed.
  • User interaction: None. No action from any user is needed.
  • Scope: Unchanged. Impact stays within the vulnerable component.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-621: Variable Extraction Error

The product uses external input to determine the names of variables into which information is extracted, without verifying that the names of the specified variables are valid.

CWE-20: Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

Affected products

  • Facebook Hhvm: up to and including 3.21.9; from 3.21.10 up to and including 3.24.5; from 3.24.6 up to and including 3.25.1

References