CVE-2026-88166Network attack vector

Authenticated code execution via integer overflow

Published Oct 13, 2026 · Updated Oct 13, 2026

Integer overflow in Microsoft SharePoint Server Subscription Edition allows remote authenticated users to execute code over a network. Microsoft identifies integer wraparound and stack-based buffer overflow, but the retrieved public record does not disclose the affected function or how network input reaches it. Exploitation requires authenticated network access without user interaction and results in code execution on the server.

CVSS severity8.8
High
EPSS probability0.82%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in Microsoft SharePoint Server Subscription Edition allows remote authenticated users to execute code over a network. Microsoft identifies integer wraparound and stack-based buffer overflow, but the retrieved public record does not disclose the affected function or how network input reaches it. Exploitation requires authenticated network access without user interaction and results in code execution on the server.

The record

CVE
CVE-2026-88166
Published
Oct 13, 2026
Updated
Oct 13, 2026
Vendor
Microsoft Corporation
Product
Microsoft SharePoint Server Subscription Edition
Classifications
CWE-190, CWE-121, T1210
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 13, 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=16.0.0 <16.0.20326.20190

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft Corporation · Microsoft SharePoint Server Subscription Editionversion=16.0.0 <16.0.20326.20190

Published CVSS scores

8.8MicrosoftCVSS:3.1/AV:N/AC:L/PR:L/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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
CWE-121Stack-based Buffer Overflow
T1210Exploitation of Remote Services

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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