CVE-2026-40420 json
Microsoft Office Click-To-Run Elevation of Privilege Vulnerability
published 5mo ago modified 14d ago also EUVD-2026-29677
- cvss
- 8.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 11%
- public exploits
- 0
- none known
Summary
Use after free in Microsoft Office allows an authorized attacker to elevate privileges locally.
Patch / fix
Is CVE-2026-40420 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 6mo ago
Exploit prediction
0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C |
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
Affected products
- Microsoft Microsoft 365 Apps for Enterprise
- Microsoft Microsoft Office 2019
- Microsoft Microsoft Office LTSC 2021
- Microsoft Microsoft Office LTSC 2024
Classification
- Weakness
-
- CWE-284 Improper Access Control
References
-
msrc.microsoft.com
/update-guide/vulnerability/CVE-2026-40420
vendor-advisory, patch
Sources
- CVE List CVE-2026-40420
- NVD CVE-2026-40420
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