Vulnerability · Published Oct 30, 2026 · Assigned by VulnCheck
CVE-2026-119602libmspack through 0.11alpha Uninitialized Memory Disclosure via MS-ZIP Decompressor Window
Low 3.7
In plain English
A low-severity security flaw in libmspack from kyz. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities).
Severity (CVSS 3.1)3.7Low
Exploit odds (30 days)0.3%top 76.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | libmspack | no fix listed | DEBIAN-CVE-2026-119602 |
| Debian:13 | libmspack | no fix listed | DEBIAN-CVE-2026-119602 |
| Debian:14 | libmspack | no fix listed | DEBIAN-CVE-2026-119602 |
| Ubuntu:22.04:LTS | libmspack | no fix listed | UBUNTU-CVE-2026-119602 |
| Ubuntu:24.04:LTS | libmspack | no fix listed | UBUNTU-CVE-2026-119602 |
| Ubuntu:26.04:LTS | libmspack | no fix listed | UBUNTU-CVE-2026-119602 |
| Ubuntu:26.10 | libmspack | no fix listed | UBUNTU-CVE-2026-119602 |
Affected products (as reported)
Weakness: CWE-908 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
References
- https://github.com/kyz/libmspack/issues/60 issue-tracking
- https://github.com/kyz/libmspack/blob/v0.11alpha/libmspack/mspack/mszipd.c#L264-L276 technical-description
- https://hackmd.io/@haindpwn/libmspack-mszip-uninit-window-info-leak third-party-advisory
- https://github.com/kyz/libmspack product
- VulnCheck Advisory: libmspack through 0.11alpha Uninitialized Memory Disclosure via MS-ZIP Decompressor Window third-party-advisory