What is CVE-2026-42901?

CVE-2026-42901 is a critical-severity vulnerability in Microsoft Entra Id, classified under Origin Validation Error. CVSS score: 10.0/10. Published 2026-05-22.

How severe is CVE-2026-42901?

Critical severity. CVSS v3 base score is 10.0 out of 10.

Vulnerability in Microsoft Entra Id

CVE-2026-42901

Origin validation error in Microsoft Entra ID allows an unauthorized attacker to elevate privileges over a network.

Published 2026-05-22 · last modified 2026-07-23.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.005 (38.6th percentile), scored 2026-10-24.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 38.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-346 — Origin Validation Error

References

Microsoft Entra ID Elevation of Privilege Vulnerability (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-42901?: CVE-2026-42901 is a critical-severity vulnerability in Microsoft Entra Id, classified under Origin Validation Error. CVSS score: 10.0/10. Published 2026-05-22.
How severe is CVE-2026-42901?: Critical severity. CVSS v3 base score is 10.0 out of 10.