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CVE-2026-100208

HIGH 7.5

Published 2026-09-25 · Last modified 2026-10-21

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

ELEVATED IMPACT

Severe if exploited (CVSS 7.5), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.5%chance of exploitation in 30 days · 39th percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

7.5CVSS 3.1 · HIGH

  • 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: Needs a race window or specific setup

✓ 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 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 Ltsc 2021 Microsoft Office Ltsc 2024 365 Apps Office 2021 Office 2024

Weakness (CWE)

  • CWE-190: : Integer Overflow or Wraparound

CVSS vector

CVSS:3.1/AV:N/AC:H/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

VendorProductVersion range
Microsoft365 Apps*
Microsoft365 Apps*
MicrosoftOffice 2021*
MicrosoftOffice 2021*
MicrosoftOffice 2024*
MicrosoftOffice 2024*

All CVSS metrics

  • HIGH 7.5 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
  • HIGH 7.5 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
  • HIGH 8.1 v3.1 · NVD Primary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Patches & mitigations

Advisories

Sources: NVD · CVE.org · EPSS