hashcat contains a heap-based buffer overflow (out-of-bounds write) in the outfile_write() function in src/outfile.c. When assembling output into a fixed-size buffer (HCBUFSIZ_LARGE, ~16 MB), the function sequentially appends the username, separator, hash, and plaintext via memcpy without validating that the accumulated length stays within the buffer capacity. When run with --username --show against a crafted hash file containing an oversized username that nearly fills the buffer, the total assembled output exceeds the buffer, causing a heap buffer overflow that can corrupt memory and crash the process.
https://github.com/hashcat/hashcat/issues/4740
https://github.com/hashcat/hashcat/commit/68f56a2d8712867a8520bf4dcf07f6145c23df89
https://github.com/hashcat/hashcat/blob/v7.1.2/src/outfile.c#L654-L668
Published: 2026-08-22
Updated: 2026-08-22
Base Score: 5.6
Vector: CVSS2#AV:L/AC:L/Au:N/C:N/I:P/A:C
Severity: Medium
Base Score: 6.1
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H
Severity: Medium
Base Score: 6.9
Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
Severity: Medium
EPSS: 0.00186