Microsoft ASP.NET Core SignalR memory leak denial of service

Severity: high · CVSS 7.5 · Published 2026-11-10

ASP.NET Core's SignalR library, which handles real-time communication in web applications, has a memory leak that allows attackers to exhaust server memory and cause service outages. An attacker can trigger the leak remotely without authentication, impacting application availability.

Technologies: Microsoft.AspNetCore.SignalR.StackExchangeRedis (NuGet). Vendors: Microsoft, NuGet.

Quick answers

Is This vulnerability exploited in the wild?
No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
How severe is This vulnerability?
High severity, with a CVSS score of 7.5, published 10 November 2026.
Which products and versions are affected?
Microsoft ASP.NET Core SignalR StackExchangeRedis 8.0.0-preview.1.23112.2 through 8.0.33; Microsoft.AspNetCore.SignalR.StackExchangeRedis (NuGet) >= 8.0.0-preview.1.23112.2, <= 8.0.33, ECOSYSTEM:introduced=8.0.0-preview.1.23112.2,last_affected=8.0.33.
Is there a fix for This vulnerability?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is This vulnerability attacked?
It is attacked over the network, in a software library.
Am I affected?
Check whether you run Microsoft ASP.NET Core SignalR StackExchangeRedis or Microsoft.AspNetCore.SignalR.StackExchangeRedis (NuGet) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A memory leak in Microsoft.AspNetCore.SignalR.StackExchangeRedis allows memory to be allocated but not released after use, enabling a denial-of-service attack. The vulnerability is reachable over the network without authentication or user interaction. An attacker can exhaust memory resources, causing the affected application to become unavailable.

Affected products

  • Microsoft ASP.NET Core SignalR StackExchangeRedis 8.0.0-preview.1.23112.2 through 8.0.33

Timeline

  • 2026-11-10: disclosed

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