CVE-2026-70183 in ASP.NET Core
Summary
by MITRE • 10/14/2026
Concurrent execution using shared resource with improper synchronization ('race condition') in ASP.NET Core allows an authorized attacker to elevate privileges over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described constitutes a race condition within the ASP.NET Core framework, specifically arising from concurrent execution contexts that interact with shared resources without adequate synchronization mechanisms. In complex web application architectures, multiple threads or requests often access common data structures, configuration states, or session objects simultaneously. When these operations are not properly serialized or protected by locks and atomic operations, a window of opportunity opens for an attacker to manipulate the state of the system through carefully timed concurrent requests. This flaw allows an authorized attacker who has already gained some level of network access to exploit timing discrepancies in how ASP.NET Core processes overlapping transactions, potentially leading to unauthorized privilege escalation.
From a technical perspective, this issue aligns with CWE-362, which defines race conditions as situations where the behavior of software depends on the relative timing of uncontrollable events such as thread scheduling or system interrupts. In the context of ASP.NET Core, shared resources might include authentication tokens, session state stores, or internal caching mechanisms used for performance optimization. If these components are modified by one request while another is in a transitional state, the application may make decisions based on inconsistent data. For instance, an attacker could manipulate permission checks or role assignments during the brief interval between validation and finalization of a user context. This exploitation technique relies heavily on precise timing to ensure that the malicious payload executes before the system can enforce consistency constraints, thereby bypassing intended security controls.
The operational impact of this vulnerability is severe because it facilitates privilege escalation over a network. An attacker who possesses valid credentials for a lower-privileged account can leverage this race condition to elevate their access rights to administrative or higher-level roles without needing additional exploits or external tools beyond standard HTTP requests. This undermines the fundamental principle of least privilege and compromises the integrity of the application's authorization model. Once elevated privileges are obtained, the attacker may gain full control over the underlying server, allowing them to exfiltrate sensitive data, modify system configurations, install backdoors, or pivot to other systems within the internal network. The ability to escalate privileges remotely makes this a critical threat vector for any organization relying on ASP.NET Core for mission-critical web services.
This vulnerability is also closely related to ATT&CK technique T1068, which covers Exploitation for Privilege Escalation, specifically when applied through software vulnerabilities rather than misconfigurations or default credentials. The exploitation path typically involves crafting multiple concurrent requests that target the same resource endpoint, aiming to trigger the race condition at a moment when security checks are bypassed due to state inconsistency. Defenders must recognize that traditional input validation and standard authentication mechanisms may not suffice against such timing-based attacks, as they do not address the concurrency flaws inherent in the application's internal logic or framework implementation.
Mitigation strategies for this vulnerability require both immediate patching and long-term architectural improvements. The primary remediation is to apply the latest security updates provided by Microsoft for ASP.NET Core, which include fixes for synchronization issues within shared resource handling. Developers should also review code that interacts with shared state in multi-threaded environments, ensuring that all critical sections are properly locked using mechanisms such as Mutexes or ReaderWriterLocks where appropriate. Implementing idempotent operations and avoiding mutable shared state across requests can further reduce the attack surface. Additionally, employing rate limiting and request throttling can help mitigate the effectiveness of race condition attacks by reducing the volume of concurrent requests an attacker can send in a short timeframe, thereby making it more difficult to achieve the precise timing required for successful exploitation. Regular security audits focusing on concurrency patterns and thread safety are essential to prevent similar vulnerabilities from being introduced during future development cycles.