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CVE-2026-78509— Microsoft Office Outlook Remote Code Execution Vulnerability

Quick assessment

Affected
Microsoft Microsoft 365 Apps for Enterprise
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Microsoft Office Outlook是美国Microsoft公司的一款集邮件收发、日程管理与联系人管理于一体的电子邮件客户端软件。 Microsoft Office Outlook存在缓冲区错误漏洞，该漏洞源于堆缓冲区溢出，可能导致未经授权的攻击者通过网络执行代码，影响Microsoft 365 Apps for Enterprise 16.0.1至16.0.20326.20138之前版本、Microsoft Office 2019 16.0.10417.20207之前版本、Microsoft

CVSS 9.8 · Critical EPSS 0.97% · P62

Possible ATT&CK Techniques 1 AI

T1204.001 · Malicious Link

Affected Version Matrix 8

VendorProduct Version RangeStatus
Microsoft Microsoft 365 Apps for Enterprise 16.0.1< 16.0.20326.20138 affected
Microsoft Microsoft Office 2019 19.0.0< 16.0.10417.20207 affected
Microsoft Microsoft Office 365 for Mac 1.0.0< 16.113.26091433 affected
Microsoft Microsoft Office LTSC 2021 16.0.1< 16.0.14334.20906 affected
Microsoft Microsoft Office LTSC 2024 16.0.0< 16.0.17932.20976 affected
Microsoft Microsoft Office LTSC for Mac 2021 16.0.1< 16.113.26091433 affected
Microsoft Microsoft Office LTSC for Mac 2024 16.0.0< 16.113.26091433 affected
Microsoft Microsoft Word 2016 16.0.1< 16.0.5569.1000 affected
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I. Basic Information for CVE-2026-78509

Vulnerability Information
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Vulnerability Title
Microsoft Office Outlook Remote Code Execution Vulnerability
Source: CVE Program / CVE List V5
Vulnerability Description
Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
堆缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
Microsoft Office Outlook 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Microsoft Office Outlook是美国Microsoft公司的一款集邮件收发、日程管理与联系人管理于一体的电子邮件客户端软件。 Microsoft Office Outlook存在缓冲区错误漏洞，该漏洞源于堆缓冲区溢出，可能导致未经授权的攻击者通过网络执行代码，影响Microsoft 365 Apps for Enterprise 16.0.1至16.0.20326.20138之前版本、Microsoft Office 2019 16.0.10417.20207之前版本、Microsoft
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Microsoft Microsoft 365 Apps for Enterprise 16.0.1 ~ 16.0.20326.20138 -
Microsoft Microsoft Office 2019 19.0.0 ~ 16.0.10417.20207 -
Microsoft Microsoft Office 365 for Mac 1.0.0 ~ 16.113.26091433 -
Microsoft Microsoft Office LTSC 2021 16.0.1 ~ 16.0.14334.20906 -
Microsoft Microsoft Office LTSC 2024 16.0.0 ~ 16.0.17932.20976 -
Microsoft Microsoft Office LTSC for Mac 2021 16.0.1 ~ 16.113.26091433 -
Microsoft Microsoft Office LTSC for Mac 2024 16.0.0 ~ 16.113.26091433 -
Microsoft Microsoft Word 2016 16.0.1 ~ 16.0.5569.1000 -

II. Public POCs for CVE-2026-78509

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III. Intelligence Information for CVE-2026-78509

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Vendor Advisories for CVE-2026-78509 (1)

Same Patch Batch · Microsoft · 2026-09-08 · 966 CVEs total

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CVE-2026-68839 9.8 CRITICAL Windows USB Mass Storage Class Driver Remote Code Execution Vulnerability
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CVE-2026-77493 9.8 CRITICAL Windows Graphics Component Remote Code Execution Vulnerability
CVE-2026-69579 9.8 CRITICAL Windows Message Queuing Remote Code Execution Vulnerability
CVE-2026-69586 9.8 CRITICAL Microsoft Windows PDF Remote Code Execution Vulnerability
CVE-2026-69768 9.8 CRITICAL Windows RNDIS Remote Code Execution Vulnerability
CVE-2026-72982 9.8 CRITICAL Windows Netlogon Remote Code Execution Vulnerability
CVE-2026-69824 9.8 CRITICAL Microsoft Standard XPS Remote Code Execution Vulnerability
CVE-2026-69910 9.8 CRITICAL Windows Hyper-V Remote Code Execution Vulnerability

Showing top 20 of 966 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Microsoft 365 Apps for Enterprise
Same vendor: Microsoft
Same weakness: CWE-122