CVE-2026-48095

HIGH

7-Zip <=26.00 NTFS Compressed Streams - Heap Buffer Overflow

Title source: manual
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-48095. PoCs published by HORKimhab.

AI-analyzed exploit summary The repository contains only placeholder files (README.md, LICENSE, .gitignore, and a template file) with no actual exploit code or technical details about CVE-2026-48095. The README is a generic template with no specific information about the vulnerability or exploit.

Description

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.

Exploits (1)

nomisec STUB
by HORKimhab · poc
https://github.com/HORKimhab/CVE-2026-48095

The repository contains only placeholder files (README.md, LICENSE, .gitignore, and a template file) with no actual exploit code or technical details about CVE-2026-48095. The README is a generic template with no specific information about the vulnerability or exploit.

Classification
Stub 95%
Attack Type
Other
Complexity
Theoretical
Reliability
Theoretical
Target: unknown
No auth needed
mistral-large-3 · analyzed Jun 18, 2026 Full analysis →

References (2)

Core 2
Core References
X_Refsource_Confirm x_refsource_confirm
https://securitylab.github.com/advisories/GHSL-2026-140_7-Zip/

Scores

CVSS v3 8.8
EPSS 0.0112
EPSS Percentile 62.8%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact total

Details

CWE
CWE-190 CWE-787
Status published
Products (2)
7-zip/7-zip < 26.01
mcmilk/7-Zip <= 26.00
Published Jun 05, 2026
Tracked Since Jun 05, 2026