NUGET · JULY 2026 · EARLY WARNING

.NET 8, 9, 10 XML Encryption DoS Vulnerability Under Investigation

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.

CVE-2026-50527GHSA-MMJF-RQRV-855VSeverity: HIGH

A denial of service vulnerability reportedly exists in the XML encryption implementation in.NET 8,.NET 9, and.NET 10. This vulnerability is under investigation.

What happened

An attacker could reportedly exploit this vulnerability by supplying crafted encrypted XML that is improperly validated, resulting in denial of service. The affected components are System.Security.Cryptography.Xml (nuget) versions >=10.0.0,<=10.0.9 for.NET 10, >=9.0.0,<=9.0.17 for.NET 9, and >=8.0.0,<=8.0.3 for.NET 8.

It is recommended to upgrade to the patched versions: 10.0.10 for.NET 10, 9.0.18 for.NET 9, and 8.0.4 for.NET 8. For more details, consult the primary sources.

How 0Day mitigates this

MATCHED TO YOUR ACTUAL DEPENDENCY GRAPH0Day matches every incoming threat signal against your GitHub organization’s full dependency graph, including transitive dependencies. If System.Security.Cryptography.Xml is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.

Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.

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