Vulnerability in Kyz Libmspack
CVE-2026-119602
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/kyz/libmspack/issues/60 (issue-tracking)
- github.com/kyz/libmspack/blob/v0.11alpha/libmspack/mspack/mszipd.c (technical-description)
- hackmd.io/@haindpwn/libmspack-mszip-uninit-window-info-leak (third-party-advisory)
- github.com/kyz/libmspack (product)
- www.vulncheck.com/advisories/libmspack-through-0-11alpha-uninitialized-memory-d… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-119602?
- CVE-2026-119602 is a low-severity vulnerability in Kyz Libmspack, classified under Use of Uninitialized Resource. CVSS score: 3.7/10. Published 2026-10-30.
- How severe is CVE-2026-119602?
- Low severity. CVSS v3 base score is 3.7 out of 10.