CVE-2020-1917: facebook hhvm Heap-based Buffer Overflow

Vulnerability summary

CVE-2020-1917 is a critical (CVSS 9.8) Heap-based Buffer Overflow vulnerability in facebook hhvm. EPSS estimates a 1.38% chance of exploitation in the next 30 days, higher than 71.8% of scored vulnerabilities.

Timeline

1. 10-03-2021
   PublishedVulnerability first disclosed.
2. 04-08-2024
   Last modifiedVulnerability information updated.

Description

xbuf_format_converter, used as part of exif_read_data, was appending a terminating null character to the generated string, but was not using its standard append char function. As a result, if the buffer was full, it would result in an out-of-bounds write. This issue affects HHVM versions prior to 4.56.3, all versions between 4.57.0 and 4.80.1, all versions between 4.81.0 and 4.93.1, and versions 4.94.0, 4.95.0, 4.96.0, 4.97.0, 4.98.0.

• CWE-122Heap-based Buffer OverflowA 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().
• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.