hashcat's fgetl() function in src/filehandling.c has a vulnerability where it writes a null terminator one byte past the caller's buffer if an input line is exactly the buffer length. This out-of-bounds heap write can be triggered by providing a specially crafted hash file, potfile, or wordlist containing a line of exactly HCBUFSIZ_LARGE bytes. The vulnerability affects multiple specific versions of hashcat. The CVSS score is 6.1, indicating a medium severity issue with potential availability impact.