CVE-2022-21986Network attack vector

Service interruption via crafted HTTP/2 or HTTP/3 requests

Published Feb 9, 2022 · Updated Jan 2, 2025

Denial of service in Microsoft .NET 5.0 and 6.0 allows remote attackers to interrupt Kestrel using crafted HTTP/2 or HTTP/3 requests. Kestrel processes certain requests in these protocols incorrectly, but Microsoft has not disclosed the specific parser state or resource operation responsible. No authentication or user interaction is required, and the documented consequence is limited to service availability.

CVSS severity7.5
High
EPSS probability3.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Microsoft .NET 5.0 and 6.0 allows remote attackers to interrupt Kestrel using crafted HTTP/2 or HTTP/3 requests. Kestrel processes certain requests in these protocols incorrectly, but Microsoft has not disclosed the specific parser state or resource operation responsible. No authentication or user interaction is required, and the documented consequence is limited to service availability.

The record

CVE
CVE-2022-21986
Published
Feb 9, 2022
Updated
Jan 2, 2025
Vendor
Microsoft
Product
.NET 6.0
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2022CVE publishedPublication date reported by the CVE source.
  2. Jan 2, 2025Record 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=6.0.0 <6.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · .NET 6.0version=6.0.0 <6.0.2
Microsoft · Visual Studio 2019 for Macversion=8.1.0 <8.10.18
Microsoft · Microsoft Visual Studio 2019 version 16.11version=16.11.0 <16.11.10
Microsoft · Microsoft Visual Studio 2022 version 17.0version=17.0.0 <17.0.6
Microsoft · Microsoft Visual Studio 2019 version 16.9version=15.0.0 <16.9.17
Microsoft · .NET 5.0version=5.0.0 <5.0.14

Published CVSS scores

7.5Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.3NISTAV:N/AC:M/Au:N/C:N/I:N/A:P

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

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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