CVE-2026-109478

Inefficient algorithmic complexity in ASP.NET Core allows an unauthorized attacker to deny service over a network.

Inefficient algorithmic complexity in ASP.NET Core allows an unauthorized attacker to deny service over a network.

Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core. This advisory provides guidance on updating affected applications and components.

Processing comma-separated HTTP header values can cause excessive allocations and resource exhaustion.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/515

CVSS Details

• Version: 3.1
• Severity: High
• Score: 7.5 (base score)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
• Weakness: CWE-407

Affected Platforms

• Platforms: Windows, Linux, macOS
• Architectures: All

<a name="affected-packages"></a>Affected Packages

The tables list affected version ranges and fixed package versions. Runtime and standalone deliveries are listed separately.

.NET 8.0 - affected runtime packages

Package | Affected version | Patched version --- | --- | --- Microsoft.AspNetCore.App.Runtime.linux-arm | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.linux-arm64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.linux-musl-arm | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.linux-musl-x64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.linux-x64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.osx-arm64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.osx-x64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.win-arm64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.win-x64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.win-x86 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34

.NET 9.0 - affected runtime packages

Package | Affected version | Patched version --- | --- | --- Microsoft.AspNetCore.App.Runtime.linux-arm | = 9.0.0-preview.1.24081.5 | 9.0.0-preview.4.24267.6 Microsoft.AspNetCore.App.Runtime.linux-arm | = 9.0.0-preview.2.24128.4 | 9.0.0-preview.4.24267.6 Microsoft.AspNetCore.App.Runtime.linux-arm | = 9.0.0-preview.3.24172.13 | 9.0.0-preview.4.24267.6 Microsoft.AspNetCore.App.Runtime.linux-arm64 | = 9.0.0-preview.1.24081.5 | 9.0.0-preview.4.24267.6 Microsoft.AspNetCore.App.Runtime.linux-arm64 | = 9.0.0-preview.2.24128.4 | 9.0.0-preview.4.24267.6 Microsoft.AspNetCore.App.Runtime.linux-arm64 | =…

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-r3qf-p3jm-8h4p. This link is maintained to preserve external references.

Original Description

Inefficient algorithmic complexity in ASP.NET Core allows an unauthorized attacker to deny service over a network.

Inefficient algorithmic complexity in ASP.NET Core allows an unauthorized attacker to deny service over a network.

Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core. This advisory provides guidance on updating affected applications and components.

Processing comma-separated HTTP header values can cause excessive allocations and resource exhaustion.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/515

CVSS Details

• Version: 3.1
• Severity: High
• Score: 7.5 (base score)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
• Weakness: CWE-407

Affected Platforms

• Platforms: Windows, Linux, macOS
• Architectures: All

<a name="affected-packages"></a>Affected Packages

The tables list affected version ranges and fixed package versions. Runtime and standalone deliveries are listed separately.

.NET 8.0 - affected runtime packages

Package | Affected version | Patched version --- | --- | --- Microsoft.AspNetCore.App.Runtime.linux-arm | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.linux-arm64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.linux-musl-arm | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.linux-musl-x64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.linux-x64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.osx-arm64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.osx-x64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.win-arm64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.win-x64 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34 Microsoft.AspNetCore.App.Runtime.win-x86 | >= 8.0.0-preview.1.23112.2, <= 8.0.33 | 8.0.34

.NET 9.0 - affected runtime packages

Package | Affected version | Patched version --- | --- | --- Microsoft.AspNetCore.App.Runtime.linux-arm | = 9.0.0-preview.1.24081.5 | 9.0.0-preview.4.24267.6 Microsoft.AspNetCore.App.Runtime.linux-arm | = 9.0.0-preview.2.24128.4 | 9.0.0-preview.4.24267.6 Microsoft.AspNetCore.App.Runtime.linux-arm | = 9.0.0-preview.3.24172.13 | 9.0.0-preview.4.24267.6 Microsoft.AspNetCore.App.Runtime.linux-arm64 | = 9.0.0-preview.1.24081.5 | 9.0.0-preview.4.24267.6 Microsoft.AspNetCore.App.Runtime.linux-arm64 | = 9.0.0-preview.2.24128.4 | 9.0.0-preview.4.24267.6 Microsoft.AspNetCore.App.Runtime.linux-arm64 | =…

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-r3qf-p3jm-8h4p. This link is maintained to preserve external references.

Original Description

Inefficient algorithmic complexity in ASP.NET Core allows an unauthorized attacker to deny service over a network.