CVE-2026-70329

HIGH 8.8 ALL-YEARS

Published 2026-08-11 · Last modified 2026-10-21 · microsoft · NVD: Analyzed

Integer overflow or wraparound in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.

ELEVATED IMPACT

Severe if exploited (CVSS 8.8), but no confirmed exploitation. Patch on a normal cadence.

Exploitation likelihood

0.8%chance of exploitation in 30 days · 57th percentile

○ In CISA KEV○ Catalogued PoC◆ SSVC: exploitation none, automatable no

Impact if exploited

8.8CVSS 3.1 · HIGH · CNA

ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

What an attacker needs

✓Access: Reachable over the network — no local access needed
✓Privileges: No account or privileges required
⚠User interaction: A user must take an action (click / open a file)
✓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

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Tracked sources are checked weekly for the full archive, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Affected

Vendors Microsoft

Products Microsoft 365 Apps For Enterprise Microsoft Office 2019 Microsoft Office Ltsc 2021 Microsoft Office Ltsc 2024 Microsoft Outlook 2016 365 Apps Office 2019 Office 2021 Office 2024 Outlook

Weakness (CWE)

CWE-190: : Integer Overflow or Wraparound

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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	Office 2019	*
Microsoft	Office 2019	*
Microsoft	Office 2021	*
Microsoft	Office 2021	*
Microsoft	Office 2024	*
Microsoft	Office 2024	*
Microsoft	Outlook	2016
Microsoft	Outlook	2016

All CVSS metrics

HIGH 8.8 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
HIGH 8.8 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

Patches & mitigations

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70329 vendor-advisorypatchPatchVendor AdvisoryCVE record · microsoft · Updated 2026-10-21T20:53:01.456Z
NVD · CVE-2026-70329 · Updated 2026-08-14T15:33:03.130

Advisories

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-56585 ADVISORYEUVD · EUVD-2026-56585

Sources: NVD · CVE.org · All sources and attribution · EPSS