Improper verification of cryptographic signature in ASP.NET Core allows an unauthorized attacker to elevate privileges over a network.

Microsoft released an out-of-band security advisory to address an ASP.NET Core elevation of privilege vulnerability. Immediate patching is recommended

The remote Fedora 43 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-018d6721a0 advisory.

    Update to .NET SDK 10.0.107 and Runtime 10.0.7

    Fixes: CVE-2026-40372

    Release Notes:

    - SDK: https://github.com/dotnet/core/blob/main/release-notes/10.0/10.0.7/10.0.107.md
    - Runtime: https://github.com/dotnet/core/blob/main/release-notes/10.0/10.0.7/10.0.7.md

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-32952baba5 advisory.

    Update to .NET SDK 10.0.107 and Runtime 10.0.7

    Fixes: CVE-2026-40372

    Release Notes:

    - SDK: https://github.com/dotnet/core/blob/main/release-notes/10.0/10.0.7/10.0.107.md
    - Runtime: https://github.com/dotnet/core/blob/main/release-notes/10.0/10.0.7/10.0.7.md

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 42 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-be6ea464d0 advisory.

    Update to .NET SDK 10.0.107 and Runtime 10.0.7

    Fixes: CVE-2026-40372

    Release Notes:

    - SDK: https://github.com/dotnet/core/blob/main/release-notes/10.0/10.0.7/10.0.107.md
    - Runtime: https://github.com/dotnet/core/blob/main/release-notes/10.0/10.0.7/10.0.7.md

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Ubuntu 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8216-1 advisory.

    Ludvig Pedersen discovered that the System.Security.Cryptography.Xml library in .NET incorrectly handled     certain XML inputs. An attacker could possibly use this issue to consume excessive resources, resulting in     a denial of service. (CVE-2026-33116, CVE-2026-26171)

    Ludvig Pedersen and Kevin Jones discovered that the System.Security.Cryptography.Xml library in .NET     incorrectly handled certain XML inputs. An attacker could possibly use this issue to cause .NET to crash,     resulting in a denial of service. (CVE-2026-32203)

    Ludvig Pedersen discovered that the System.Net.Mail component in .NET incorrectly handled certain inputs.
    An attacker could possibly use this issue to perform a network spoofing attack. (CVE-2026-32178)

    It was discovered that the Microsoft.AspNetCore.DataProtection library in .NET did not properly verify     cryptographic signatures under certain conditions. A remote attacker could possibly use this issue to     elevate privileges. (CVE-2026-40372)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-1634 advisory.

    Improper verification of cryptographic signature in ASP.NET Core allows an unauthorized attacker to     elevate privileges over a network. (CVE-2026-40372)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Ubuntu 24.04 LTS / 25.10 host has packages installed that are affected by a vulnerability as referenced in the USN-8215-1 advisory.

    It was discovered that the Microsoft.AspNetCore.DataProtection library in .NET did not properly verify     cryptographic signatures under certain conditions. A remote attacker could possibly use this issue to     elevate privileges.

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Improper verification of cryptographic signature in ASP.NET Core allows an unauthorized attacker to     elevate privileges over a network. (CVE-2026-40372)

Note that Nessus relies on the presence of the package as reported by the vendor.

The Microsoft ASP.NET installations on the remote host are missing a security update. It is, therefore, affected by an elevation of privileges vulnerability:

  - Improper verification of cryptographic signature in ASP.NET Core allows an unauthorized attacker to elevate privileges over a network. (CVE-2026-40372)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
313736	Fedora 43 : dotnet10.0 (2026-018d6721a0)	Nessus	Fedora Local Security Checks	critical
313722	Fedora 44 : dotnet10.0 (2026-32952baba5)	Nessus	Fedora Local Security Checks	critical
313714	Fedora 42 : dotnet10.0 (2026-be6ea464d0)	Nessus	Fedora Local Security Checks	critical
311794	Ubuntu 26.04 LTS : .NET vulnerabilities (USN-8216-1)	Nessus	Ubuntu Local Security Checks	high
311326	Amazon Linux 2023 : aspnetcore-runtime-10.0, aspnetcore-runtime-dbg-10.0, aspnetcore-targeting-pack-10.0 (ALAS2023-2026-1634)	Nessus	Amazon Linux Local Security Checks	critical
310931	Ubuntu 24.04 LTS / 25.10 : .NET vulnerability (USN-8215-1)	Nessus	Ubuntu Local Security Checks	critical
310798	Linux Distros Unpatched Vulnerability : CVE-2026-40372	Nessus	Misc.	critical
310116	Microsoft ASP.NET (April 2026)	Nessus	Windows : Microsoft Bulletins	critical

Detections

Analytics

CVE-2026-40372

critical

Tenable Plugins

critical

critical

critical

high

critical

critical

critical

critical