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


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.19% (9th percentile)

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  • Snyk IDSNYK-ALPINE324-7ZIP-17376612
  • published19 Jun 2026
  • disclosed5 Jun 2026

Introduced: 5 Jun 2026

CVE-2026-48102  (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 9.11 through 26.00 contain a heap out-of-bounds read of up to 3 bytes in the UDF disc image handler's File Identifier Descriptor parser. In CFileId::Parse (CPP/7zip/Archive/Udf/UdfIn.cpp), after validating size < 38 + idLen + impLen and advancing processed to 38 + impLen + idLen, the alignment-padding loop reads p[processed] while incrementing up to 3 times to reach a 4-byte boundary, and the processed <= size bounds check only runs after the loop. When (38 + impLen + idLen) % 4 != 0 and 38 + impLen + idLen == size, the loop reads 1 to 3 bytes past the end of the exact-size heap buffer allocated via buf.Alloc((size_t)item.Size). The UDF handler is registered for .iso and .udf files and auto-detected by signature, and the OOB read triggers during Open() when listing or extracting a crafted UDF image. Impact is limited to information disclosure (a 1-bit oracle per OOB byte via open/fail behavior) and denial of service (crash under hardened allocators); there is no write primitive. Version 26.01 fixes the issue.

CVSS Base Scores

version 3.1