The vulnerability lies in the mapper_map function of gbsplay 0.0.103, where ROM bank indexes that exceed the allowable ROM size are not rejected. This leads to an underflowed bank length and allows the bank_get function to read beyond the intended heap buffer. An attacker can supply a malicious .gbr, .gbs, or .gb file with crafted bank indexes to force the player to read far past the ROM buffer, resulting in a crash. Consequently, the primary impact is a denial of service for any user who loads such a file.

The affected product is gbsplay from mmitch, version 0.0.103. No other versions or vendors are reported as affected.

The CVSS score of 6.8 indicates moderate severity. EPSS is not available and the vulnerability is not listed in the CISA KEV catalog, suggesting limited publicly known exploitation. However, the attack vector requires the user to supply a specially crafted game file, making the vulnerability more relevant to local or potentially remote attacks if the software accepts files over a network. Without an official patch, the risk remains that an attacker can cause a denial of service by using malicious files. While full remote exploitation may be limited, the availability of the vulnerability makes it advisable to handle the file input carefully or update the software.