CVE-2026-78509: microsoft 365_apps, microsoft microsoft_365, microsoft office_2019

CVSS 9.8 (critical) · published 2026-09-08

Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.

Affected products (NVD): microsoft 365_apps, microsoft microsoft_365, microsoft office_2019, microsoft office_2021, microsoft office_2024, microsoft word

Weakness: CWE-122

Source: NVD CVE-2026-78509

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78509

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