CVE-2026-96225 in .NET
Summary
by MITRE
Improper link resolution before file access ('link following') in .NET allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described constitutes a classic race condition known as Time of Check to Time of Use, specifically manifesting through improper link resolution prior to file access within the Microsoft .NET framework. This flaw arises when the application performs security checks on a symbolic link or junction point before actually accessing the target resource it points to. In this scenario, an attacker who has already gained authorized local access can exploit the window between the initial check and the subsequent use of the path. By manipulating the filesystem during this narrow timeframe, the attacker can redirect the file operation from the intended safe location to a sensitive system file or configuration directory that requires higher privileges than those held by the compromised account.
From a technical perspective, this issue stems from the framework's handling of absolute paths and symbolic links without enforcing atomicity in security validation. When .NET resolves a path for operations such as reading, writing, or deleting files, it may validate permissions against the link itself rather than ensuring that the target remains unchanged during execution. If an attacker can create a malicious symlink pointing to a critical system file after the permission check but before the actual I/O operation occurs, the application will inadvertently perform actions with elevated privileges on behalf of the lower-privileged user. This mechanism effectively bypasses standard access control lists and allows for local privilege escalation from a low-integrity process to SYSTEM or administrative levels.
The operational impact of this vulnerability is severe as it enables an authenticated attacker to escalate their privileges on the affected system without requiring additional exploits or external network vectors. Once elevated, the attacker gains full control over the operating system, allowing them to install malware, steal sensitive data, modify security policies, and maintain persistent access. This significantly expands the blast radius of a compromised workstation or server, turning a minor breach into a complete compromise of the infrastructure. The risk is particularly acute in environments where multiple users share systems or where services run with varying privilege levels, as it provides a reliable path to break out of sandboxed or restricted user contexts.
This vulnerability aligns closely with Common Weakness Enumeration (CWE) categories such as CWE-59: Improper Link Resolution Before File Access and CWE-367: Time-of-check Time-of-use Race Condition in Security Features. In the context of the MITRE ATT&CK framework, this behavior is indicative of techniques related to Privilege Escalation via Local Exploitation, specifically leveraging race conditions or symlink attacks to bypass access controls. Defense strategies must focus on mitigating these risks by ensuring that file operations are atomic and secure against path manipulation.
To mitigate this vulnerability, organizations should apply the latest security patches provided by Microsoft for their .NET runtime environments immediately. Additionally, developers implementing custom file handling logic within applications should avoid relying solely on standard library functions for privileged operations without additional validation. Best practices include using safe API calls that resolve links atomically, verifying the final target path against a whitelist of allowed directories after resolution rather than before, and employing strict access control lists on sensitive system files to prevent unauthorized modification even if symlink attacks succeed. Regular auditing of file permissions and monitoring for unusual changes in symbolic link targets can also help detect exploitation attempts early.