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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| hashcat | hashcat | ≤ 7.1.2 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | hashcat | No fix yet | — |
| Debian 13 | hashcat | No fix yet | — |
| Debian 12 | hashcat | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | hashcat | No fix yet | — |
| Ubuntu 26.04 LTS | hashcat | No fix yet | — |
| Ubuntu 24.04 LTS | hashcat | No fix yet | — |
| Ubuntu 22.04 LTS | hashcat | No fix yet | — |
| Ubuntu 20.04 LTS | hashcat | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | hashcat | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | hashcat | 7.1.2+git942-1.1 | openSUSE-SU-2026:12181-1 |
| openSUSE Leap 16.0 | hashcat | 7.1.2+git942-bp160.1.1 | openSUSE-SU-2026:22138-1 |
Advisories 2
- openSUSE-SU-2026:22138-1 Security update for hashcat SUSE / openSUSE Security Updates · Oct 20, 2026
- openSUSE-SU-2026:12181-1 hashcat-7.1.2+git942-1.1 on GA media SUSE / openSUSE Security Updates · Oct 19, 2026
References
- GitHub Issue #4740 issue-tracking
- https://github.com/hashcat/hashcat product
- https://github.com/hashcat/hashcat/commit/68f56a2d8712867a8520bf4dcf07f6145c23df89 patch
- https://github.com/hashcat/hashcat/blob/v7.1.2/src/outfile.c#L654-L668 technical-description
- VulnCheck Advisory: hashcat through 7.1.2 Heap Buffer Overflow in outfile_write() via Oversized Username third-party-advisory