Buffer overflow in Microsoft 365_copilot
CVE-2026-42831
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
Vulnerability class: Buffer Overflow
EPSS: 0.001 (19.5th percentile) — read the EPSS interpretation.
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.
Affected products
- Microsoft 365_copilot
- Microsoft Office For Android — versions 16.0.1
- Microsoft Office Ltsc For Mac 2021 — versions 16.0.1
- Microsoft Office Ltsc For Mac 2024 — versions 16.0.0
- Microsoft Office — versions 2021, 2024
- Microsoft Office_long_term_servicing_channel — versions 2021
Weakness classification (CWE)
References
- Microsoft Office Remote Code Execution Vulnerability (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-42831?
- CVE-2026-42831 is a high-severity vulnerability in Microsoft 365_copilot, classified under Heap-based Buffer Overflow. CVSS score: 7.8/10. Published 2026-05-12.
- How severe is CVE-2026-42831?
- High severity. CVSS v3 base score is 7.8 out of 10.