Advisoriesby IbisMicrosoftCVE-2026-78521
Microsoft Office Word: heap buffer overflow
Fix: upgrade to 16.0.20326.20138 or later (6 fixed versions below)
Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network.
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| Microsoft 365 Apps for Enterprise Product | >= 16.0.1, < 16.0.20326.20138 | 16.0.20326.20138 |
| Microsoft Office 2019 Product | >= 19.0.0, < 16.0.10417.20207 | 16.0.10417.20207 |
| Microsoft Office 365 for Mac Product | >= 1.0.0, < 16.113.26091433 | 16.113.26091433 |
| Microsoft Office LTSC 2021 Product | >= 16.0.1, < 16.0.14334.20906 | 16.0.14334.20906 |
| Microsoft Office LTSC 2024 Product | >= 16.0.0, < 16.0.17932.20976 | 16.0.17932.20976 |
| Microsoft Office LTSC for Mac 2021 Product | >= 16.0.1, < 16.113.26091433 | 16.113.26091433 |
| Microsoft Office LTSC for Mac 2024 Product | >= 16.0.0, < 16.113.26091433 | 16.113.26091433 |
| Microsoft Word 2016 Product | >= 16.0.1, < 16.0.5569.1000 | 16.0.5569.1000 |
Details and references
- CVSS 3.1
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Severity from
- the vendor (its own CVE record or advisory)
- Weakness
- CWE-122