Description
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.
References6
Metrics
- CVSS 3.1
-
6.1
MEDIUM
Score source: CNA
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H - CVSS 4.0
-
6.9
MEDIUM
Score source: CNA
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 11 · as of 9 November 2026
- CWE
- CWE-120
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.