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VulnerabilityPublished

CVE-2026-48101: mcmilk 7-Zip · Use of Uninitialized Resource

Affects mcmilk 7-ZipSource CVE Database V5

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Not known to be exploited · CVSS 6.5 Medium : upgrade to 26.01 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 26.01
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 5 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade mcmilk 7-Zip to 26.01.

Affected software

ProductAffectedFixed in
mcmilk7-ZipAffected
  • >=9.21 <26.01
Fixed in
  • 26.01

AI-suggested

Version 26.0.1 of 7-Zip fixes this vulnerability by properly handling buffer initialization and read operations in the UEFI capsule parser. Users should upgrade to 7-Zip 26.0.1 or later to remediate this issue. Patch status is not explicitly confirmed in the vendor advisory, but the description states version 26.0.1 fixes the issue. No other mitigations are indicated.

Description

7-Zip is a file archiver with a high compression ratio. Versions 9.21 through 26.00 contain an An uninitialized memory disclosure vulnerability in the UEFI capsule (.scap) parser in 7-Zip. The OpenCapsule function allocates a heap buffer of attacker-declared CapsuleImageSize (up to 1 GiB) without zero-initialization, then reads the file contents into it with ReadStream_FALSE whose return value is silently discarded. If the file is truncated, the unread tail of the buffer retains uninitialized heap memory, which is then exposed as extracted file content via GetStream. Version 26.0.1 fixes the issue.

References

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