Buffer overflow in Microsoft 365 Copilot

CVE-2025-30388

Heap-based buffer overflow in Windows Win32K - GRFX allows an unauthorized attacker to execute code locally.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.042 (90.6th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 91st percentile — 90.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-30388: held from 0.039 to 0.042.

EPSS over last 30 days · oldest: 0.039 · newest: 0.042 · change: +0.003

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-30388?
CVE-2025-30388 is a high-severity vulnerability in Microsoft 365 Copilot, classified under Heap-based Buffer Overflow. CVSS score: 7.8/10. Published 2025-05-13.
How severe is CVE-2025-30388?
High severity. CVSS v3 base score is 7.8 out of 10.
Is CVE-2025-30388 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.