Bug 2521341 (CVE-2026-68768)

Summary: CVE-2026-68768 hashcat: hashcat: Heap Buffer Overflow leading to Denial of Service via oversized username
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in hashcat. A vulnerability exists where the software attempts to write more data than its allocated memory can hold, specifically in the function responsible for writing output files. This can happen when processing a specially crafted hash file containing an excessively long username, combined with specific command-line options. An attacker could exploit this to corrupt memory, leading to a denial of service by crashing the hashcat application.
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Bug Depends On: 2521895    
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Description OSIDB Bzimport 2026-08-22 14:32:14 UTC 
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.