What is CVE-2026-21264?

CVE-2026-21264 is a critical-severity vulnerability in Microsoft Account, classified under Cross-site Scripting. CVSS score: 9.3/10. Published 2026-01-22.

How severe is CVE-2026-21264?

Critical severity. CVSS v3 base score is 9.3 out of 10.

XSS in Microsoft Account

CVE-2026-21264

Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Account allows an unauthorized attacker to perform spoofing over a network.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.004 (29.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N.

Affected products

Microsoft Account
Microsoft Account

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

secure@microsoft.com (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-21264?: CVE-2026-21264 is a critical-severity vulnerability in Microsoft Account, classified under Cross-site Scripting. CVSS score: 9.3/10. Published 2026-01-22.
How severe is CVE-2026-21264?: Critical severity. CVSS v3 base score is 9.3 out of 10.