CVE-2026-26171Network attack vector

Service interruption via unsafe EncryptedXml transforms

Published Apr 14, 2026 · Updated Apr 14, 2026

Uncontrolled resource consumption in Microsoft .NET 8, 9.0, and 10.0 allows remote attackers to interrupt services via crafted XML. EncryptedXml processes unsafe transforms in attacker-controlled encrypted XML without adequately restricting external or recursive entity expansion, consuming excessive resources. Reachability requires an application that uses an affected System.Security.Cryptography.Xml release and passes untrusted encrypted XML into EncryptedXml.

CVSS severity7.5
High
EPSS probability1.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in Microsoft .NET 8, 9.0, and 10.0 allows remote attackers to interrupt services via crafted XML. EncryptedXml processes unsafe transforms in attacker-controlled encrypted XML without adequately restricting external or recursive entity expansion, consuming excessive resources. Reachability requires an application that uses an affected System.Security.Cryptography.Xml release and passes untrusted encrypted XML into EncryptedXml.

The record

CVE
CVE-2026-26171
Published
Apr 14, 2026
Updated
Apr 14, 2026
Vendor
Microsoft
Product
.NET 9.0
Classifications
CWE-400, CWE-611, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 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=9.0.0 <9.0.15

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · .NET 9.0version=9.0.0 <9.0.15
Microsoft · .NET 10.0version=10.0.0 <10.0.6
Microsoft · .NET 8version=8.0.0 <8.0.26

Published CVSS scores

7.5MicrosoftCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Red Hat Security Data APICVSS: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.

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

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-611Improper Restriction of XML External Entity Reference
T1499.004Application or System Exploitation

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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