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CVE-2026-110602 kyz CVE debrief

libmspack through 0.11alpha contains an uninitialized pointer free vulnerability in kwajd_open() in mspack/kwajd.c. This vulnerability frees unzeroed filename and extra pointers on header read errors, allowing attackers to supply a truncated, empty, or wrong-signature KWAJ file to crash the process or obtain an arbitrary-free memory corruption primitive. Defenders should assess exposure and prioritize patching, especially in systems handling KWAJ files. The vulnerability's impact includes potential process crashes or arbitrary-free memory corruption, emphasizing the need for verification of patching and vulnerability status.

Vendor
kyz
Product
libmspack
CVSS
MEDIUM 5.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-14
Original CVE updated
2026-10-14
Advisory published
2026-10-14
Advisory updated
2026-10-14

Who should care

Defenders responsible for libmspack installations, especially in systems handling KWAJ files, should assess exposure and prioritize patching. This includes operators of affected systems, platform administrators, vulnerability management teams, and security teams. They should verify and apply patches, restrict access to KWAJ files, and monitor systems for potential crashes or anomalies. Additionally, they should review compensating controls for exposed and

Why it matters

Defenders should prioritize verifying and patching libmspack installations, especially in systems handling KWAJ files, due to the potential for process crashes or arbitrary-free memory corruption.

  • Potential process crashes or arbitrary-free memory corruption
  • Verification of patching and vulnerability status is required
  • Restrictive access controls for KWAJ files may be necessary
  • Monitoring for anomalies or crashes is recommended

Technical summary

The vulnerability is caused by an uninitialized pointer free in kwajd_open() in mspack/kwajd.c. Attackers can supply a truncated, empty, or wrong-signature KWAJ file to crash the process or obtain an arbitrary-free memory corruption primitive. This issue is particularly concerning for systems handling KWAJ files, as it could lead to process crashes or arbitrary-free memory corruption. The vulnerability is a result of the library's handling of KWAJ file headers, where uninitialized pointers are freed on read errors.

Defensive priority

Defenders should prioritize verifying and patching libmspack installations, especially in systems handling KWAJ files.

Recommended defensive actions

  • Verify and apply patches for libmspack installations
  • Restrict access to KWAJ files
  • Monitor systems for potential crashes or anomalies
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability is caused by an uninitialized pointer free in kwajd_open() in mspack/kwajd.c. Attackers can supply a truncated, empty, or wrong-signature KWAJ file to crash the process or obtain an arbitrary-free memory corruption primitive.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-110602 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-110602

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-110602 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-110602

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • libmspack through 0.11alpha Uninitialized Pointer Free via kwajd_open Error Path

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/110xxx/CVE-2026-110602.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://github.com/kyz/libmspack/commit/4d868504114346aa767d435fbb89a8b76603493f

    Supplemental source - patch

  • Source reference

    Unverified legacy reference

    URL: https://github.com/kyz/libmspack/blob/v0.11alpha/libmspack/mspack/kwajd.c

    Supplemental source - technical-description

  • Source reference

    Unverified legacy reference

    URL: https://hackmd.io/@haind-pwn/libmspack-kwaj-uninitialized-free

    Supplemental source - third-party-advisory

  • Source reference

    Unverified legacy reference

    URL: https://www.vulncheck.com/advisories/libmspack-through-0-11alpha-uninitialized-pointer-free-via-kwajd-open-error-path

    Supplemental source - third-party-advisory

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.