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CVE-2026-48104 (GCVE-0-2026-48104)

Vulnerability from cvelistv5 – Published: 2026-06-05 15:56 – Updated: 2026-06-05 19:08
VLAI
Title
GHSL-2026-120: 7-Zip SquashFS BlockToNode uninitialized heap read
Summary
7-Zip is a file archiver with a high compression ratio. Versions 9.18 through 26.00 contain an uninitialized heap read in the SquashFS archive handler caused by a sparsely populated index array. In the SquashFS handler, _blockToNode is allocated with capacity for every metadata block but populated only when an inode crosses a block boundary, so a crafted image with few inodes spanning many blocks leaves most slots holding raw heap contents (the underlying allocator does not zero-initialize POD storage). When OpenDir looks up an attacker-influenced blockIndex (derived from the RootInode superblock field), it reads two of these uninitialized slots and passes them as the left/right bounds of a binary search over _nodesPos, which dereferences the midpoint without bounds checking; if the resulting value happens to match the search key, the returned index is used to read a full node struct from _nodes whose fields feed further directory parsing, forming a chained OOB read primitive that is heap-layout-dependent and not reliably triggerable. The SquashFS handler is enabled by default in stock 7z.dll and the issue triggers during Open() with no interaction beyond opening the file; impact is denial of service from wild-pointer dereference and potential heap information disclosure, with no write primitive. Version 26.01 fixes the issue.
Severity
4.2 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:L
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-05 19:08 UTC
CWE
  • CWE-908 - Use of Uninitialized Resource
  • CWE-125 - Out-of-bounds Read
Assigner
References
Impacted products
Vendor Product Version CPE status
mcmilk 7-Zip Affected: >= 9.18, < 26.01
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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