CVE-2026-26127: .NET Denial of Service Vulnerability

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-10 · updated 2026-06-19
Weakness: CWE-125

Description

Out-of-bounds read in .NET allows an unauthorized attacker to deny service over a network.

Affected products

Microsoft .NET: from 10.0.0 before 10.0.4; from 9.0.0 before 9.0.14 — fixed in 10.0.4, 9.0.14
Microsoft Bcl.Memory: from 9.0.0 before 9.0.14; from 10.0.0 before 10.0.4 — fixed in 10.0.4, 9.0.14
Microsoft .NET: from 10.0.0 before 10.0.4 — fixed in 10.0.4
Microsoft .NET 9.0: from 9.0.0 before 9.0.14 — fixed in 9.0.14
Microsoft.Bcl.Memory: from 10.0.0 before 10.0.4 — fixed in 10.0.4

How to fix

Upgrade to a fixed version: Microsoft .NET 10.0.4, 9.0.14; Microsoft Bcl.Memory 10.0.4, 9.0.14; Microsoft .NET 10.0.4; Microsoft .NET 9.0 9.0.14; Microsoft.Bcl.Memory 10.0.4. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26127

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