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).
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. This could cause the program to overwrite unintended variables.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Hhvm | * | 3.21.9 (including) | |
| Hhvm | 3.21.10 (including) | 3.24.5 (including) | |
| Hhvm | 3.24.6 (including) | 3.25.1 (including) | |
| Hhvm | Ubuntu | artful | * |
| Hhvm | Ubuntu | bionic | * |
| Hhvm | Ubuntu | upstream | * |
| Hhvm | Ubuntu | xenial | * |
For example, in PHP, extraction can be used to provide functionality similar to register_globals, a dangerous functionality that is frequently disabled in production systems. Calling extract() or import_request_variables() without the proper arguments could allow arbitrary global variables to be overwritten, including superglobals. Similar functionality is possible in other interpreted languages, including custom languages.