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CVE-2026-48095— GHSL-2026-140_7-Zip: 7-Zip has a heap buffer overflow via NTFS compressed stream buffer under-allocation

Quick assessment

Affected
mcmilk 7-Zip
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

7-Zip是7-Zip开源的一个压缩软件。 7-Zip 26.00及之前版本存在缓冲区错误漏洞，该漏洞源于NTFS压缩流缓冲区分配不足，可能导致攻击者造成任意代码执行或应用崩溃。

CVSS 8.8 · High EPSS 0.63% · P48

Affected Version Matrix 1

VendorProduct Version RangeStatus
mcmilk 7-Zip <= 26.00 affected
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I. Basic Information for CVE-2026-48095

Vulnerability Information
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Vulnerability Title
GHSL-2026-140_7-Zip: 7-Zip has a heap buffer overflow via NTFS compressed stream buffer under-allocation
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
Source: CVE Program / CVE List V5
Vulnerability Title
7-Zip 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
7-Zip是7-Zip开源的一个压缩软件。 7-Zip 26.00及之前版本存在缓冲区错误漏洞，该漏洞源于NTFS压缩流缓冲区分配不足，可能导致攻击者造成任意代码执行或应用崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
mcmilk 7-Zip <= 26.00 -

II. Public POCs for CVE-2026-48095

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III. Intelligence Information for CVE-2026-48095

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Vendor Advisories for CVE-2026-48095 (1)

Same Patch Batch · mcmilk · 2026-06-05 · 8 CVEs total

CVE-2026-48112 6.5 MEDIUM GHSL-2026-122 7-Zip Ar SYMDEF OOB Read
CVE-2026-48101 6.5 MEDIUM GHSL-2026-117: 7-Zip UEFI Capsule uninitialized heap memory disclosure
CVE-2026-48092 4.3 MEDIUM 7-Zip SquashFS Fragment Offset Overflow (GHSL-2026-116)
CVE-2026-48111 4.3 MEDIUM GHSL-2026-121 7-Zip UEFI DEPEX OOB Read
CVE-2026-48103 4.3 MEDIUM GHSL-2026-119 7-Zip WIM SecurityId OOB read
CVE-2026-48104 4.2 MEDIUM GHSL-2026-120: 7-Zip SquashFS BlockToNode uninitialized heap read
CVE-2026-48102 3.1 LOW GHSL-2026-118: 7-Zip UDF Field OOB Read

IV. Related Vulnerabilities

Same product: 7-Zip
Same vendor: mcmilk
Same weakness: CWE-787

V. Comments for CVE-2026-48095

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