What is CVE-2025-64677?

CVE-2025-64677 is a high-severity vulnerability in Microsoft Office Out-Of-Box Experience, classified under Cross-site Scripting. CVSS score: 8.2/10. Published 2025-12-18.

How severe is CVE-2025-64677?

High severity. CVSS v3 base score is 8.2 out of 10.

XSS in Microsoft Office Out-Of-Box Experience

CVE-2025-64677

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

Vulnerability class: XSS (Cross-Site Scripting)

Published 2025-12-18 · last modified 2026-10-01.

CVSS v3 metric

CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N.

EPSS exploit prediction

EPSS: 0.005 (42.3th percentile), scored 2026-10-03.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 42nd percentile — 42.3% 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-79 — Cross-site Scripting

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2025-64677 (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2025-64677?: CVE-2025-64677 is a high-severity vulnerability in Microsoft Office Out-Of-Box Experience, classified under Cross-site Scripting. CVSS score: 8.2/10. Published 2025-12-18.
How severe is CVE-2025-64677?: High severity. CVSS v3 base score is 8.2 out of 10.