CVE-2026-70291
CRITICAL 9.8Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
Severe if exploited (CVSS 9.8), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
1.3%chance of exploitation in 30 days · 71st percentile
Impact if exploited
9.8CVSS 3.1 · CRITICAL
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityHigh
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
Search for new PoCs
Search GitHub now — results may be empty or unverified.
Tracked sources are checked daily for recent CVEs, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.
Data snapshot:
Affected
Vendors Microsoft
Products Microsoft 365 Apps For Enterprise Microsoft Office 365 For Mac Microsoft Office Ltsc 2021 Microsoft Office Ltsc 2024 Microsoft Office Ltsc For Mac 2021 Microsoft Office Ltsc For Mac 2024 365 Apps Microsoft 365 Office 2021 Office 2024
Weakness (CWE)
- CWE-122: : Heap-based Buffer Overflow
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
References and research data (JSON)
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Microsoft | 365 Apps | * |
| Microsoft | 365 Apps | * |
| Microsoft | Microsoft 365 | * |
| Microsoft | Office 2021 | * |
| Microsoft | Office 2021 | * |
| Microsoft | Office 2021 | * |
| Microsoft | Office 2024 | * |
| Microsoft | Office 2024 | * |
| Microsoft | Office 2024 | * |
All CVSS metrics
- CRITICAL 9.8 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C - CRITICAL 9.8 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
References
Patches & mitigations
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70291 CVE record · microsoft · Updated 2026-10-25T18:43:06.360Z
NVD · CVE-2026-70291 · Updated 2026-10-15T21:17:46.443
Advisories
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-99717 EUVD · EUVD-2026-99717