CVE-2026-25667Public exploitNetwork attack vector

CPU exhaustion via unterminated HTTP/3 stream loop

Published Mar 19, 2026 · Updated Mar 19, 2026

Denial of service in ASP.NET Core Kestrel in Microsoft .NET 8.0 before 8.0.22 and .NET 9.0 before 9.0.11 allows remote attackers to exhaust CPU. Http3ControlStream.HandleEncodingDecodingTask loops on Input.ReadAsync after a peer ends an empty QPACK encoder or decoder stream, repeatedly advancing an already completed buffer instead of terminating. Remote attackers need HTTP/3 reachability but no credentials; one QUIC STREAM frame can saturate CPU, and repeated frames deny service to benign clients.

CVSS severity7.5
High
EPSS probability3.00%
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 ASP.NET Core Kestrel in Microsoft .NET 8.0 before 8.0.22 and .NET 9.0 before 9.0.11 allows remote attackers to exhaust CPU. Http3ControlStream.HandleEncodingDecodingTask loops on Input.ReadAsync after a peer ends an empty QPACK encoder or decoder stream, repeatedly advancing an already completed buffer instead of terminating. Remote attackers need HTTP/3 reachability but no credentials; one QUIC STREAM frame can saturate CPU, and repeated frames deny service to benign clients.

The record

CVE
CVE-2026-25667
Published
Mar 19, 2026
Updated
Mar 19, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 19, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS: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.

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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 exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.003Application Exhaustion Flood

Public exploit references

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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