CVE-2026-70175 in ASP.NET Core
Summary
by MITRE • 10/14/2026
Improper authentication in ASP.NET Core allows an unauthorized attacker to elevate privileges over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described constitutes a critical failure in the identity verification mechanisms within applications built on the ASP.NET Core framework, specifically categorized under CWE-287 as Improper Authentication. This flaw arises when the application fails to correctly verify the credentials or security tokens presented by an incoming request before granting access to protected resources or administrative functions. In many instances of this vulnerability class, the issue stems from misconfigured middleware pipelines where authentication checks are bypassed due to incorrect ordering of components, such as placing authorization logic after routing decisions that allow unauthenticated paths to execute privileged code. Alternatively, it may result from a failure to validate cryptographic signatures on JSON Web Tokens or session cookies, allowing an attacker to forge valid credentials for arbitrary users. The core technical deficiency lies in the application's inability to distinguish between authenticated and anonymous requests when processing sensitive operations, effectively rendering any access control measures ineffective against network-based attacks.
From an operational perspective, this vulnerability enables a remote unauthenticated attacker to escalate privileges from a standard user or guest role to that of an administrator or system operator without possessing valid login credentials. By exploiting the authentication bypass, the attacker can perform actions intended only for trusted entities, such as modifying application configuration files, accessing sensitive databases, executing arbitrary code on the server, or manipulating business logic data. The impact is severe because it compromises the integrity and confidentiality of the entire system. Since ASP.NET Core applications often handle significant amounts of user data and critical business processes, this privilege escalation can lead to full system compromise, allowing the attacker to pivot into internal networks, exfiltrate proprietary information, or deploy ransomware. The attack vector is typically remote over a network, requiring no physical access or prior local foothold, which significantly increases the risk profile for organizations deploying these applications in internet-facing environments.
This type of vulnerability aligns with several entries in the MITRE ATT&CK framework, particularly T1078 Valid Accounts and T1068 Exploitation for Privilege Escalation. Attackers leverage this flaw to establish persistent access by creating backdoor accounts or modifying existing permissions, ensuring continued control even if initial entry points are patched. The lack of proper authentication checks also violates fundamental security principles outlined in OWASP Top 10, specifically A07:2021 Identification and Authentication Failures. To mitigate this risk, developers must ensure that the ASP.NET Core middleware pipeline is correctly ordered, with authentication services invoked before authorization policies to guarantee that every request undergoes rigorous identity verification. Implementing multi-factor authentication for administrative interfaces adds an additional layer of defense against credential-based attacks. Furthermore, applying principle of least privilege ensures that even if a vulnerability is exploited, the potential damage is contained by restricting the permissions granted to default application identities and service accounts. Regular security audits using static analysis tools can help identify misconfigured routes or missing authorization attributes before deployment into production environments.