Resource exhaustion in Microsoft .Net
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, because of an incorrect exit condition for HTTP/3 Encoder/Decoder stream processing.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.042 (90.6th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 91st percentile — 90.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.030 · newest: 0.042 · change: +0.012
Affected products
Weakness classification (CWE)
References
- github.com/IsaJafarov/Kestrel-DoS (Exploit, Third Party Advisory)
- github.com/dotnet/aspnetcore/commit/96ccc40a0e095424b19506e8268b9b1a3e23d6a7 (Patch)
- github.com/IsaJafarov/Q3Fuzz
Frequently asked questions
- What is CVE-2026-25667?
- CVE-2026-25667 is a high-severity vulnerability in Microsoft .Net, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-03-19.
- How severe is CVE-2026-25667?
- High severity. CVSS v3 base score is 7.5 out of 10.