Type Vulnerability
Confirm whether the affected software runs in your estate before deciding on action.
Microsoft · Memory corruption
Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to disclose information locally
CVE-2026-66810
What this means
This is rated medium severity (5.5 out of 10). There is no confirmed exploitation of it yet. Ask IT whether Microsoft 365 Apps, Microsoft Microsoft 365 and Microsoft Office 2019, and 3 more are in your estate.
Full vendor description
Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
Scoring and exploitation
5.5/ 10
CVSS 3.1 base scoreMedium
Exploitable only with local access without any account, but only if a user takes an action, such as opening a file or link. High impact on confidentiality.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Exploitability
Longer bar: easier to attack
Attack vectorLocalAV:L
Attack complexityLowAC:L
Privileges requiredNonePR:N
User interactionRequiredUI:R
ScopeUnchangedS:U
Impact
Longer bar: more harm
ConfidentialityHighC:H
IntegrityNoneI:N
AvailabilityNoneA:N
- Not reported
- Exploited in the wild
- Not confirmed in the
- Not reported
Weaknesses
CWE-122
Affected products ()
- Microsoft 365 Apps
- Microsoft Microsoft 365
- Microsoft Office 2019
- Microsoft Office 2021
- Microsoft Office 2024
- Microsoft Word
Show the raw CPE strings (13)
- cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*
- cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*
- cpe:2.3:a:microsoft:microsoft_365:-:*:*:*:*:macos:*:*
- cpe:2.3:a:microsoft:office_2019:-:*:*:*:*:*:x64:*
- cpe:2.3:a:microsoft:office_2019:-:*:*:*:*:*:x86:*
- cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:-:x64:*
- cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:-:x86:*
- cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:macos:-:*
- cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x64:*
- cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x86:*
- cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:macos:-:*
- cpe:2.3:a:microsoft:word:2016:*:*:*:*:*:x64:*
- cpe:2.3:a:microsoft:word:2016:*:*:*:*:*:x86:*
References
1 link from the CVE record, grouped by site; the vendor's advisory comes first.
msrc.microsoft.com1 linkVendor advisory
- CVE-2026-66810 (opens in a new tab)Vendor Advisory