CVE-2026-48095 (GCVE-0-2026-48095)
Vulnerability from cvelistv5 – Published: 2026-06-05 13:57 – Updated: 2026-06-08 19:10
VLAI
EPSS
VEX
Title
GHSL-2026-140_7-Zip: 7-Zip has a heap buffer overflow via NTFS compressed stream buffer under-allocation
Summary
7-Zip is a file archiver with a high compression ratio. Versions 26.00 and prior contain a heap buffer overflow vulnerability caused by an under-allocation in the NTFS compressed stream buffer (GetCuSize shift UB), potentially allowing attackers to cause arbitrary code execution or application crashes. CInStream::GetCuSize() in the NTFS handler computes the compression-unit buffer size as (UInt32)1 << (BlockSizeLog + CompressionUnit), and a crafted image with ClusterSizeLog >= 28 and CompressionUnit == 4 drives the exponent to 32, which is undefined behavior and collapses on x86/x64 so _inBuf is allocated as 1 byte. ReadStream_FALSE then writes up to 256 MB of attacker-controlled data into that 1-byte buffer in 64 KB iterations, and because the CInStream object sits only 304 bytes after _inBuf, its vtable pointer is overwritten and the next dispatched call achieves a vtable hijack. On 32-bit builds the overflow is unconditionally reached; on 64-bit it requires the parallel 8 GB _outBuf allocation to succeed, otherwise failing closed to denial of service. The NTFS handler is enabled by default in stock 7z.dll and, via signature-based fallback matching "NTFS " at offset 3, will open a crafted image regardless of file extension during extraction or testing. Version 26.01 fixes the issue.
Severity
8.8 (High)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-08 19:10 UTC
Assigner
GitHub_M
CNA
References
2 references
| URL | Tags |
|---|---|
| https://securitylab.github.com/advisories/GHSL-20… | x_refsource_CONFIRM |
| https://sourceforge.net/p/sevenzip/discussion/457… | x_refsource_MISC |
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Browse all ATT&CK techniques and the vulnerabilities related to each.
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