CVE-2025-21171Network attack vector

Remote code execution through crafted web requests

Published Jan 14, 2025 · Updated Jun 9, 2026

Heap-based buffer overflow in Microsoft .NET 9.0.0 allows remote attackers to execute code by sending a crafted web request. Microsoft has not published the affected runtime routine or the incorrect memory operation that processes the request. The request must reach a .NET 9.0.0 application acting as a web server under high-complexity conditions; successful exploitation executes code in the server context.

CVSS severity8.1
High
EPSS probability1.70%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in Microsoft .NET 9.0.0 allows remote attackers to execute code by sending a crafted web request. Microsoft has not published the affected runtime routine or the incorrect memory operation that processes the request. The request must reach a .NET 9.0.0 application acting as a web server under high-complexity conditions; successful exploitation executes code in the server context.

The record

CVE
CVE-2025-21171
Published
Jan 14, 2025
Updated
Jun 9, 2026
Vendor
Microsoft
Product
PowerShell 7.5
Classifications
CWE-122, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 14, 2025CVE publishedPublication date reported by the CVE source.
  2. Jun 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=7.5.0 <7.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · PowerShell 7.5version=7.5.0 <7.5.0
Microsoft · .NET 9.0version=9.0.0 <9.0.1
Microsoft · Microsoft Visual Studio 2022 version 17.12version=17.12.0 <17.12.4
Microsoft · Microsoft Visual Studio 2022version=17.10.0 <17.10.10; version=17.6.0 <17.6.22; version=17.8.0 <17.8.17

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 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-122Heap-based Buffer Overflow
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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