CVE-2026-83645Network attack vector

Service interruption via unbounded resource allocation

Published Oct 13, 2026 · Updated Oct 13, 2026

Resource exhaustion in Microsoft AD FS allows remote attackers to interrupt federation services via unauthenticated network requests. The CNA identifies allocation without limits or throttling but does not disclose the affected handler or triggering input. An AD FS service must be reachable over the network; the record does not specify whether denial of service causes a hang, crash, or another interruption.

CVSS severity7.5
High
EPSS probability1.10%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Microsoft AD FS allows remote attackers to interrupt federation services via unauthenticated network requests. The CNA identifies allocation without limits or throttling but does not disclose the affected handler or triggering input. An AD FS service must be reachable over the network; the record does not specify whether denial of service causes a hang, crash, or another interruption.

The record

CVE
CVE-2026-83645
Published
Oct 13, 2026
Updated
Oct 13, 2026
Vendor
Microsoft Corporation
Product
Windows Server 2019
Classifications
CWE-770, T1499
Attack vector
network
Privileges
unauthenticated

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=10.0.17763.0 <10.0.17763.9376

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft Corporation · Windows Server 2019version=10.0.17763.0 <10.0.17763.9376
Microsoft Corporation · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.33650
Microsoft Corporation · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.9612
Microsoft Corporation · Windows Server 2012 (Server Core installation)version=6.2.9200.0 <6.2.9200.26434
Microsoft Corporation · Windows Server 2012version=6.2.9200.0 <6.2.9200.26434
Microsoft Corporation · Windows Server 2016version=10.0.14393.0 <10.0.14393.9612
Microsoft Corporation · Windows Server 2012 R2 (Server Core installation)version=6.3.9600.0 <6.3.9600.23470
Microsoft Corporation · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.9376
Microsoft Corporation · Windows 10 Version 1607version=10.0.14393.0 <10.0.14393.9612
Microsoft Corporation · Windows Server 2022version=10.0.20348.0 <10.0.20348.5761
Microsoft Corporation · Windows Server 2025version=10.0.26100.0 <10.0.26100.33650
Microsoft Corporation · Windows 10 Version 1809version=10.0.17763.0 <10.0.17763.9376
Microsoft Corporation · Windows Server 2012 R2version=6.3.9600.0 <6.3.9600.23470

Published CVSS scores

7.5MicrosoftCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499Endpoint Denial of Service

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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