CVE-2026-78509
CVSS v3
9.8
CRITICAL
EPSS Score
1.0 %
exploit probability, as of 2026-09-28
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
Technical details
- Published
- 2026-09-08
- Last Modified
- 2026-09-09
Frequently asked questions
What is CVE-2026-78509?
Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
Is CVE-2026-78509 actively exploited?
Active exploitation of CVE-2026-78509 has not been confirmed. Its EPSS score was 1.0% on 2026-09-28, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2026-78509?
CVE-2026-78509 has a CVSS v3 base score of 9.8 (CRITICAL severity).
Is CVE-2026-78509 affecting your environment?
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