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Fencer Vulns
medium 4.2

CVE-2026-48104 json

GHSL-2026-120: 7-Zip SquashFS BlockToNode uninitialized heap read

published 2026-06-05 5 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-34853

cvss
4.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

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.

Patch / fix

  • 7-zip 7-zip 26.01
  • 7zip Debian 12 22.01+really26.01+dfsg-0+deb12u1
  • 7zip Debian 14 26.01+dfsg-1
  • p7zip Debian 12 16.02+really26.01+dfsg-0+deb12u1
  • p7zip Debian 13 16.02+transitional.1

debian advisories DEBIAN-CVE-2026-48104

  • 7zip SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 26.01-150400.9.6.1
  • 7zip SLES for SAP applications 16.0, SLES 16.0 26.01-160000.1.1

suse advisories SUSE-SU-2026:2696-1SUSE-SU-2026:22347-1

  • 7zip openSUSE Tumbleweed 26.02-2.1
  • 7zip openSUSE Leap 16.0 26.01-160000.1.1

opensuse advisories openSUSE-SU-2026:11502-1openSUSE-SU-2026:21038-1

  • 7zip Alpine 3.24 26.01-r0

alpine advisories ALPINE-CVE-2026-48104

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-48104 updated cvss 5.5

7-Zip: uninitialized heap read in the SquashFS archive handler

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • securitylab.github.com https://securitylab.github.com/advisories/GHSL-2026-115_GHSL-2026-122_7-zip/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 4.2 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:L

Affected products

  • mcmilk 7-Zip

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.