Description

Numeric truncation error in Windows DNS allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.7",
  "pubDate": "2026-08-11T17:18:29.350Z",
  "pubdate": "2026-08-11T17:18:29.350Z",
  "executiveSummary": "A numeric truncation error vulnerability exists within Windows DNS, potentially allowing an authorized local attacker to elevate privileges.\nThe vulnerability type is classified as a numeric truncation error, which arises when data is cast or copied into a smaller data type without adequate boundary or size validation, leading to integer wrapping or data truncation.\nSuccessful exploitation of this security flaw grants the attacker elevated privileges on the target system, potentially leading to unauthorized access, system compromise, and administrative control over the affected Windows DNS component.\nThe affected product is Windows DNS. The scope of impact is limited to local execution context.\nThe risk implications are significant, as successful local privilege escalation typically allows attackers to bypass standard operating system access controls, execute arbitrary code with elevated permissions, tamper with system configurations, and deploy persistent mechanisms.\nAttacker capabilities require local execution access on the target machine. Furthermore, the attacker must already be an authorized user to initiate the attack sequence.\nExploitation requirements include local authentication and the ability to interact directly with the vulnerable Windows DNS service or its associated interfaces.",
  "technicalDetails": "The root cause of the vulnerability stems from a numeric truncation error within the Windows DNS service.\nNumeric truncation vulnerabilities typically occur when an application performs arithmetic operations or size calculations using larger integer types and subsequently assigns the result to a smaller integer variable without appropriate range checks.\nThis improper type casting or truncation can cause the variable to wrap around or represent a significantly smaller value than intended, leading to memory corruption issues such as heap-based or stack-based buffer overflows during subsequent memory allocation or data copy operations.\nThe vulnerable component is the Windows DNS service binary or associated dynamic link libraries responsible for parsing, processing, or handling specific DNS-related data structures and requests.\nExploitation involves the manipulation of input parameters or data sizes provided to the vulnerable Windows DNS component.\nAn authorized local attacker crafts a specialized payload or input sequence designed to trigger the numeric truncation condition.\nThe attack flow proceeds as follows: First, the local attacker authenticates to the local system and establishes communication with the vulnerable Windows DNS service or interface. Second, the attacker supplies specially formatted input or requests containing values that trigger the numeric truncation error during internal size calculations or memory allocation routines. Third, the resulting miscalculated buffer size leads to a memory corruption condition, such as a heap overflow, when data is copied into the undersized buffer. Fourth, the attacker leverages this memory corruption to manipulate execution flow or overwrite critical data structures within the context of the DNS service process.\nBecause the Windows DNS service often operates with high privileges, successfully hijacking the control flow allows the attacker to execute arbitrary code with those elevated system privileges.\nThe privilege requirements mandate that the attacker possesses local access and authorization to interact with the system.\nThe network exposure is restricted to a local attack vector, as remote exploitation is not facilitated by this specific numeric truncation flaw.\nPost-exploitation impact includes complete local privilege escalation, allowing the attacker to perform administrative actions, access sensitive system resources, modify system files, and compromise the integrity of the host operating system."
}