CVE-2026-55007Network attack vector

Unauthenticated code execution via double free

Published Sep 8, 2026 · Updated Sep 9, 2026

A double free in Microsoft Exchange Server 2019 CU14, 2019 CU15, and Subscription Edition RTM allows remote attackers to execute code. Microsoft has not published the affected component, allocation lifecycle, or network input that causes the same memory allocation to be freed twice. No authentication or user interaction is required, but exploitation has high complexity and successful attacks can run code in the server process context.

CVSS severity8.1
High
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A double free in Microsoft Exchange Server 2019 CU14, 2019 CU15, and Subscription Edition RTM allows remote attackers to execute code. Microsoft has not published the affected component, allocation lifecycle, or network input that causes the same memory allocation to be freed twice. No authentication or user interaction is required, but exploitation has high complexity and successful attacks can run code in the server process context.

The record

CVE
CVE-2026-55007
Published
Sep 8, 2026
Updated
Sep 9, 2026
Vendor
Microsoft
Product
Microsoft Exchange Server 2019 Cumulative Update 14
Classifications
CWE-415, T1190
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

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Is a vulnerable build present?

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

  1. Affected versionversion=15.02.0.0 <15.02.1544.046

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Exchange Server 2019 Cumulative Update 14version=15.02.0.0 <15.02.1544.046
Microsoft · Microsoft Exchange Server Subscription Edition RTMversion=15.02.0.0 <15.02.2562.049
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 15version=15.02.0.0 <15.02.1748.051

Published CVSS scores

8.1MicrosoftCVSS:3.1/AV:N/AC:H/PR:N/UI:N/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-415Double Free
T1190Exploit Public-Facing Application

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

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Your stack

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