What is CVE-2026-124229?

CVE-2026-124229 is a medium-severity vulnerability in Microsoft 365 Apps For Enterprise, classified under Deserialization of Untrusted Data. CVSS score: 6.6/10. Published 2026-11-10.

How severe is CVE-2026-124229?

Medium severity. CVSS v3 base score is 6.6 out of 10.

Deserialization in Microsoft 365 Apps For Enterprise

CVE-2026-124229

Deserialization of untrusted data in Microsoft Office Excel allows an unauthorized attacker to execute code with a physical attack.

Vulnerability class: Insecure Deserialization

Published 2026-11-10 · last modified 2026-11-10.

CVSS v3 metric

CVSS v3 base score 6.6 (Medium). Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-124229 (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-124229?: CVE-2026-124229 is a medium-severity vulnerability in Microsoft 365 Apps For Enterprise, classified under Deserialization of Untrusted Data. CVSS score: 6.6/10. Published 2026-11-10.
How severe is CVE-2026-124229?: Medium severity. CVSS v3 base score is 6.6 out of 10.