CVE-2026-110602: libmspack through 0.11alpha Uninitialized Pointer Free via kwajd_open Error Path

Severity: medium (CVSS 6.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-14 · updated 2026-10-16
Weakness: CWE-824

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.

Affected products

kyz libmspack: through 0.11alpha

References

https://github.com/kyz/libmspack/blob/v0.11alpha/libmspack/mspack/kwajd.c#L111-L181
https://github.com/kyz/libmspack/commit/4d868504114346aa767d435fbb89a8b76603493f
https://hackmd.io/@haind-pwn/libmspack-kwaj-uninitialized-free
https://www.vulncheck.com/advisories/libmspack-through-0-11alpha-uninitialized-pointer-free-via-kwajd-open-error-path
https://hackmd.io/@haind-pwn/libmspack-kwaj-uninitialized-free

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