CVE-2026-78519Network attack vector

Remote code execution via uninitialized resource use

Published Sep 8, 2026 · Updated Sep 9, 2026

Use of an uninitialized resource in Microsoft Office Outlook allows remote attackers to execute code through network-delivered content. Microsoft has not published the affected resource, processing locus, or operation that consumes it before initialization. Exploitation requires user interaction and runs attacker-controlled code with the privileges of the affected Outlook process.

CVSS severity8.8
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Use of an uninitialized resource in Microsoft Office Outlook allows remote attackers to execute code through network-delivered content. Microsoft has not published the affected resource, processing locus, or operation that consumes it before initialization. Exploitation requires user interaction and runs attacker-controlled code with the privileges of the affected Outlook process.

The record

CVE
CVE-2026-78519
Published
Sep 8, 2026
Updated
Sep 9, 2026
Vendor
Microsoft
Product
Microsoft Office 2019
Classifications
CWE-908, T1204
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=19.0.0 <16.0.10417.20207

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Office 2019version=19.0.0 <16.0.10417.20207
Microsoft · Microsoft Outlook 2016version=16.0.0.0 <16.0.5569.1000
Microsoft · Microsoft Office LTSC 2021version=16.0.1 <16.0.14334.20906
Microsoft · Microsoft Office LTSC 2024version=16.0.0 <16.0.17932.20976
Microsoft · Microsoft 365 Apps for enterpriseversion=16.0.1 <16.0.20326.20138

Published CVSS scores

8.8MicrosoftCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource
T1204User Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo