CVE-2026-65797
Summary
by MITRE • 08/11/2026
Numeric truncation error in Windows DNS allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a numeric truncation error within the windows dns server implementation that enables local privilege escalation for authorized attackers who possess legitimate access to the system. The flaw occurs when the dns service processes numeric values during internal operations, specifically during authentication or authorization workflows where integer overflow or truncation conditions can be exploited by malicious actors with existing user-level privileges. The vulnerability stems from inadequate input validation and handling of numeric data types within the dns server components, creating opportunities for attackers to manipulate integer values that control access controls or privilege levels. This type of vulnerability typically falls under cwe-190 integer overflow or wraparound as defined in the common weakness enumeration catalog, where insufficient bounds checking allows numeric values to exceed their intended range and produce unexpected behavior within the system's authorization mechanisms.
The operational impact of this vulnerability extends beyond simple privilege escalation as it represents a critical security weakness that can be leveraged by attackers who have already established a foothold on the target system. Once exploited, an attacker can gain elevated privileges that would normally require administrative access or specific authentication credentials, effectively bypassing normal security controls and access restrictions within the dns server environment. The local nature of this vulnerability means that attackers must first obtain valid user credentials or physical access to the system before attempting exploitation, but the privilege escalation aspect significantly amplifies the potential damage that can be achieved. This type of vulnerability is particularly concerning because it operates at the system level where dns servers typically maintain critical network infrastructure controls and may have elevated privileges necessary for network-wide operations.
From a defensive perspective, this vulnerability requires immediate attention through proper patch management protocols as microsoft has likely released security updates addressing the specific numeric truncation conditions within the dns server implementation. Organizations should prioritize applying relevant security patches to all windows dns server implementations while also implementing monitoring solutions that can detect anomalous numeric processing patterns or unauthorized privilege escalation attempts. Network administrators should consider implementing additional access controls and privilege separation measures around dns server configurations, ensuring that only essential personnel have administrative access to these critical infrastructure components. The exploitation of this vulnerability aligns with attack techniques described in the mitre att&ck framework under privilege escalation tactics where attackers leverage software vulnerabilities to gain elevated system privileges, specifically targeting system services and components that maintain elevated permissions within network environments.
The root cause analysis reveals that this vulnerability exists due to insufficient validation of numeric inputs during critical dns server operations, particularly in areas where authentication tokens or access control lists are processed. The truncation error allows attackers to manipulate integer values in ways that bypass normal authorization checks, potentially enabling them to impersonate privileged users or gain access to restricted system resources. Effective mitigation strategies include not only applying security patches but also implementing comprehensive logging and monitoring of dns server operations, particularly around authentication events and privilege-related activities. Security teams should also conduct regular vulnerability assessments targeting dns server configurations and implement proper code review processes for custom dns implementations that may contain similar numeric handling issues. The vulnerability demonstrates the importance of robust input validation and proper integer boundary checking in system components that handle sensitive authorization functions, aligning with industry best practices for secure coding standards and defensive programming techniques.