What is CVE-2026-117556?

CVE-2026-117556 is a security advisory published by Microsoft Security Response Center (MSRC) with Medium severity. zchunk before 1.5.5 Heap Out-of-Bounds Read via read_preface()

Which CVE IDs does CVE-2026-117556 cover?

CVE-2026-117556 covers the following CVE IDs: CVE-2026-117556. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of CVE-2026-117556?

CVE-2026-117556 has a CVSS v3 base score of 4.3, published by Microsoft Security Response Center (MSRC).

Which products are affected by CVE-2026-117556?

CVE-2026-117556 affects 1 product, including: azl3 mtools 4.0.43-2 on Azure Linux 3.0.

CVE-2026-117556MediumCVSS 4.3

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Vendor

Microsoft Security Response Center (MSRC)

Published

October 29, 2026

Last Modified

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🔗 CVE IDs covered (1)

CVE-2026-117556 →

🎯 Affected products1

azl3 mtools 4.0.43-2 on Azure Linux 3.0

✅ Remediation

KBRelease Notes (Security Update) — fixed build 1.5.5-1

🔗 References (2)

advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-117556
referencehttps://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade