Description
libmspack through 0.11alpha contains an uninitialized pointer free vulnerability in kwajd_open() in mspack/kwajd.c that frees unzeroed filename and extra pointers on header read errors. Attackers can supply a truncated, empty, or wrong-signature KWAJ file to crash the process or obtain an arbitrary-free memory corruption primitive.
References5
- github.com/kyz/libmspack/blob/v0.11alpha/libmspack/mspack/kwajd…
- github.com/kyz/libmspack/commit/4d868504114346aa767d435fbb89a8b…
- hackmd.io/@haind-pwn/libmspack-kwaj-uninitialized-free
- www.vulncheck.com/advisories/libmspack-through-0-11alpha-uninit…
- hackmd.io/@haind-pwn/libmspack-kwaj-uninitialized-free
Metrics
- CVSS 3.1
-
6.3
MEDIUM
Score source: CNA
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H - CVSS 4.0
-
5.8
MEDIUM
Score source: CNA
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 15 · as of 11 November 2026
- CWE
- CWE-824
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.