---
id: CVE-2026-119602
title: >-
  libmspack through 0.11alpha Uninitialized Memory Disclosure via MS-ZIP
  Decompressor Window
summary: >-
  libmspack through 0.11alpha contains an uninitialized memory disclosure
  vulnerability in the MS-ZIP decompressor that allows attackers to leak heap
  data via unchecked back-reference distances. Attackers can supply a crafted
  MS-ZIP CAB fi…
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-908
vendor: kyz
product: libmspack
affected:
  - libmspack <= 0.11alpha
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-30T15:21:16.087677Z'
published: '2026-10-30'
updated: '2026-10-30'
sourceUpdated: '2026-10-30T15:53:29.159Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-119602'
references:
  - url: 'https://github.com/kyz/libmspack/issues/60'
  - url: >-
      https://github.com/kyz/libmspack/blob/v0.11alpha/libmspack/mspack/mszipd.c#L264-L276
  - url: 'https://hackmd.io/@haindpwn/libmspack-mszip-uninit-window-info-leak'
  - url: 'https://github.com/kyz/libmspack'
  - url: >-
      https://www.vulncheck.com/advisories/libmspack-through-0-11alpha-uninitialized-memory-disclosure-via-ms-zip-decompressor-window
    label: >-
      VulnCheck Advisory: libmspack through 0.11alpha Uninitialized Memory
      Disclosure via MS-ZIP Decompressor Window
tags:
  - cve.org
epss: 0.00307
epssPercentile: 0.23632
ingestedAt: '2026-11-05T16:07:30.515Z'
---

## Overview

libmspack through 0.11alpha contains an uninitialized memory disclosure vulnerability in the MS-ZIP decompressor that allows attackers to leak heap data via unchecked back-reference distances. Attackers can supply a crafted MS-ZIP CAB file whose first block begins with a back-reference, causing cabd->extract() to write up to 32 KiB of stale heap memory into extracted output.

## Affected

- `libmspack <= 0.11alpha`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.