CVE-2026-97778
Microsoft 365 Apps: integer overflow
- Risk score
- 67/100
- CVSS
- 8.8 v3.1
- Exploit chance (30 days)
- 0.6%
- Published
- 13 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- Integer overflow or wraparound in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.
- Affected
- Microsoft 365 Apps
- Fix
- Apply the vendor's security update; see the linked advisory.
- Exploitation
- No known exploitation
Story map
At a glance
Microsoft 365 Apps: Amber, patch this week. Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
The flaws
- CVE-2026-97778: Integer overflow (CVSS 8.8 · EPSS 1%)
- CVE-2026-70242: Heap buffer overflow (CVSS 9.8 · EPSS 1%)
- CVE-2026-100209: Use-after-free (CVSS 8.8 · EPSS 1%)
- CVE-2026-100210: Heap buffer overflow (CVSS 8.8 · EPSS 1%)
The fix
Fix: Apply the vendor's security update; see the linked advisory.
Who is exposed: Microsoft 365 Apps
Where it stands
- No known exploitation
- 1 outlet covering it
How it unfolded
- 14 Oct, Infosecurity Magazine (press): Microsoft Breaks Patch Tuesday Record Again with 1400+ CVEs
Connects to
- Same weakness: Integer overflow (CWE-190). 125 other warnings in 30 days
- Same product: Earlier Microsoft 365 Apps warnings. 161 in the last 90 days
- Reported alongside: Microsoft Windows Command Injection Vulnerability. CVE-2026-96951 · in 1 of the same article
Why it is Amber
- CVSS 8.8 high
- Remotely exploitable without logging in
References
Original description
Integer overflow or wraparound in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.
Last activity 13 Oct 2026. Patch Forecast updates every hour.