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CVE-2026-25667

Microsoft .net denial of service

7.5 HIGHPublic exploitEPSS 4.18%
  1. Published19 Mar 2026

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Microsoft .net≥ 8.0.0 < 8.0.22 · ≥ 9.0.0 < 9.0.11

Remediation

Fixed in
Microsoft .net≥ 8.0.22

References

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Frequently asked

Is CVE-2026-25667 being actively exploited?

CVE-2026-25667 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 4.18%.

How severe is CVE-2026-25667?

CVE-2026-25667 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 4.18% probability of exploitation.

Which products are affected by CVE-2026-25667?

Affected products include Microsoft .net.

How do I fix CVE-2026-25667?

Upgrade affected software to a fixed version, for example Microsoft .net 8.0.22 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-25667 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.