SB2026071577 - Multiple vulnerabilities in Microsoft ASP.NET Core

Description

This security bulletin contains information about 3 vulnerabilities.

1) Incorrect Implementation of Authentication Algorithm (CVE-ID: CVE-2026-47300)

CWE-ID: CWE-303 - Incorrect Implementation of Authentication Algorithm

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to escalate privileges.

The vulnerability exists due to incorrect implementation of authentication algorithm in ASP.NET Core. A remote user can gain elevated privileges on the target system.

2) Allocation of Resources Without Limits or Throttling (CVE-ID: CVE-2026-56170)

CWE-ID: CWE-770 - Allocation of Resources Without Limits or Throttling

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to unrestricted resource allocation in ASP.NET Core. A remote attacker can bypass implemented security restrictions and perform a denial of service (DoS) attack.

3) Authentication Bypass by Assumed-Immutable Data (CVE-ID: CVE-2026-47303)

CWE-ID: CWE-302 - Authentication Bypass by Assumed-Immutable Data

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to escalate privileges.

The vulnerability exists due to authentication bypass by assumed-immutable data in ASP.NET Core. A remote user can gain elevated privileges on the target system.

Remediation

Install update from vendor's website.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-47300
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56170
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-47303