The function number_format is vulnerable to a heap overflow issue when its second argument ($dec_points) is excessively large. The internal implementation of the function will cause a string to be created with an invalid length, which can then interact poorly with other functions. This affects all supported versions of HHVM (3.30.1 and 3.27.5 and below).
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
The product writes data past the end, or before the beginning, of the intended buffer.
| Link | Tags |
|---|---|
| https://github.com/facebook/hhvm/commit/190ffdf6c8b1ec443be202c7d69e63a7e3da25e3 | third party advisory patch |
| https://hhvm.com/blog/2019/01/14/hhvm-3.30.2.html | release notes vendor advisory |