High severity · published Mar 19, 2026
CVE-2026-25667
ASP.NET Core Kestrel in Microsoft .NET 8.0 before 8.0.22 and .NET 9.0 before 9.0.11 allows a remote attacker to cause excessive CPU consumption by sending a crafted QUIC packet,…
7.5
CVSS
3.1%
EPSS
No
On KEV
Description
ASP.NET Core Kestrel in Microsoft .NET 8.0 before 8.0.22 and .NET 9.0 before 9.0.11 allows a remote attacker to cause excessive CPU consumption by sending a crafted QUIC packet, because of an incorrect exit condition for HTTP/3 Encoder/Decoder stream processing.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)3.1% · higher than 88% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NE
.net · Microsoft
8.0.0 before 8.0.22; 9.0.0 before 9.0.11 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-25667
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-25667
Exploit
https://github.com/IsaJafarov/Kestrel-DoS
github.com
https://github.com/IsaJafarov/Q3Fuzz
Patch
https://github.com/dotnet/aspnetcore/commit/96ccc40a0e095424b19506e8268b9b1a3e23d6a7#diff-667d5b3693f93a0f706ab211428998b210862f9b885d917104d2013118312626
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