What is CVE-2025-62459?

CVE-2025-62459 is a high-severity vulnerability in Microsoft 365 Defender Portal, classified under Cross-site Scripting. CVSS score: 8.3/10. Published 2025-11-20.

How severe is CVE-2025-62459?

High severity. CVSS v3 base score is 8.3 out of 10.

XSS in Microsoft 365 Defender Portal

CVE-2025-62459

Microsoft Defender Portal Spoofing Vulnerability

Vulnerability class: XSS (Cross-Site Scripting)

Published 2025-11-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L.

EPSS exploit prediction

EPSS: 0.003 (21.6th percentile), scored 2026-10-04.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 21.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2025-62459 (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2025-62459?: CVE-2025-62459 is a high-severity vulnerability in Microsoft 365 Defender Portal, classified under Cross-site Scripting. CVSS score: 8.3/10. Published 2025-11-20.
How severe is CVE-2025-62459?: High severity. CVSS v3 base score is 8.3 out of 10.