CVE-2026-69822 in Windows
Summary
by MITRE • 09/09/2026
Numeric truncation error in Windows Kerberos allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability described involves a numeric truncation error within the Microsoft Kerberos implementation, specifically affecting how certain integer values are processed during authentication and ticket validation processes. This flaw arises when large numerical inputs or specific edge-case parameters exceed the capacity of the data types used to store them locally within the application logic. Instead of properly validating these bounds or handling overflow conditions gracefully, the system truncates the higher-order bits of the number, resulting in a significantly smaller value than intended. In the context of Kerberos, which serves as the primary authentication protocol for Windows Active Directory environments, such miscalculations can lead to incorrect assessments of ticket validity, expiration times, or access control permissions. Because this logic is executed during the local processing of security tokens and assertions, an attacker who has already gained a foothold on the system with standard user privileges can exploit this discrepancy to manipulate how the operating system interprets their authorization level.
From a technical perspective, this issue aligns closely with CWE-190 Integer Overflow or Wraparound, where arithmetic operations produce results that exceed the maximum value for an integer type, leading to unintended behavior due to truncation. The operational impact is severe because it facilitates local privilege escalation without requiring physical access or remote exploitation vectors. An authorized attacker, defined as any user account with valid credentials on the target machine, can craft specific requests or manipulate existing tickets in a way that triggers this truncation error. By doing so, they may bypass security checks designed to restrict administrative actions, effectively granting themselves elevated rights such as SYSTEM-level access or domain administrator privileges depending on the context of the compromised token. This undermines the fundamental principle of least privilege and allows lateral movement within an enterprise network if the escalated account is used to target other systems.
This vulnerability maps directly to MITRE ATT&CK technique T1078 Valid Accounts, specifically under local accounts, as it relies on existing legitimate credentials rather than exploiting a remote code execution flaw or phishing vector. It also relates to privilege escalation techniques where an attacker leverages misconfigurations or software bugs to gain higher-level access. The absence of proper input validation and boundary checking in the Kerberos service component highlights a gap in secure coding practices regarding integer handling. Such errors are particularly dangerous because they often go undetected by standard security monitoring tools that focus on network anomalies rather than local logic flaws within authentication services.
Mitigation strategies primarily involve applying vendor-supplied patches as soon as they become available, ensuring that the Kerberos service and associated cryptographic libraries are updated to address these integer handling deficiencies. Organizations should also implement strict access controls and monitor for unusual privilege escalation activities using endpoint detection and response solutions. Regular auditing of user permissions helps ensure that even if an attacker gains initial access, their ability to exploit this specific flaw is limited by robust group policy configurations. Furthermore, adopting secure coding standards that mandate rigorous testing for integer overflows and truncation errors during the development lifecycle can prevent similar vulnerabilities from being introduced into critical authentication infrastructure in the future.