Out-of-bounds Read Affecting 7zip package, versions <26.01-r0


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.23% (13th percentile)

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  • Snyk IDSNYK-ALPINE324-7ZIP-17376619
  • published19 Jun 2026
  • disclosed5 Jun 2026

Introduced: 5 Jun 2026

CVE-2026-48103  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

Upgrade Alpine:3.24 7zip to version 26.01-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream 7zip package and not the 7zip package as distributed by Alpine. See How to fix? for Alpine:3.24 relevant fixed versions and status.

7-Zip is a file archiver with a high compression ratio. Versions 9.34 through 26.00 contain an off-by-one heap out-of-bounds read in the WIM (Windows Imaging) archive handler's security descriptor lookup. In CHandler::GetSecurity (CPP/7zip/Archive/Wim/WimHandler.cpp), the per-image SecurOffsets table holds numEntries + 1 cumulative offsets, but the check securityId >= SecurOffsets.Size() admits securityId == numEntries, and the function then reads SecurOffsets[securityId + 1], fetching one UInt32 past the end of the heap-allocated CRecordVector (which performs no bounds checking on operator[]). The securityId is attacker-controlled at offset +0xC of any directory entry in WIM metadata, and the handler is registered for .wim, .swm, .esd, and .ppkg and enabled by default in stock 7z.dll; the OOB triggers zero-click in the GUI because 7zFM.exe's ListView calls GetRawProp(kpidNtSecure) for every item during listing (ASan-confirmed), and is also reachable via CLI listing with 7zz l -slt. Impact is limited to denial of service under hardened allocators and minor information disclosure, since the OOB value is only consumed arithmetically as a length and is not surfaced to the attacker; there is no write primitive.

CVSS Base Scores

version 3.1