CVE-2026-97843 in Windows
Summary
by MITRE • 10/15/2026
Out-of-bounds read in DNS Server allows an authorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability described constitutes a critical security flaw within the Domain Name System (DNS) server infrastructure, specifically manifesting as an out-of-bounds read condition. This type of memory safety error occurs when the software attempts to access data at a memory location that is outside the boundaries of the intended buffer or array. In the context of DNS servers, which are fundamental components of internet infrastructure responsible for translating domain names into IP addresses, such flaws can have severe implications for system stability and information confidentiality. The specific nature of this vulnerability allows an attacker who has already gained authorized access to exploit the memory mismanagement issue, thereby reading sensitive data from adjacent memory regions that were not intended to be accessed by the application logic.
From a technical perspective, out-of-bounds reads are often categorized under CWE-125, which defines Out-of-Bounds Read as accessing memory beyond the end of an array or buffer without causing a crash but potentially leaking information. Unlike out-of-bounds writes, which can lead to code execution and arbitrary command injection, out-of-bounds reads primarily facilitate information disclosure. The DNS server processes various query types and responses that involve complex data structures. If input validation is insufficient or if pointer arithmetic calculations are flawed during the parsing of these packets, the application may read memory contents adjacent to the target buffer. This can result in the leakage of internal state variables, cryptographic keys, stack canaries, or other sensitive operational data stored in the process memory space.
The impact of this vulnerability is significant because it undermines the confidentiality aspect of the CIA triad for organizations relying on their DNS infrastructure. An authorized attacker, who might be a compromised user account or an insider threat with legitimate network access, can leverage this flaw to exfiltrate sensitive information over the network. This disclosed data could include internal network topology details, authentication tokens, or private keys used for secure communications such as DNSSEC signing. The ability to read arbitrary memory locations effectively turns the DNS server into a side-channel attack vector, allowing the attacker to reconstruct critical security contexts that should remain isolated within the application's protected memory space.
In terms of threat modeling and industry frameworks, this vulnerability aligns with ATT&CK technique T1005, which refers to Data from Local System. The exploitation path typically involves the attacker sending specially crafted DNS queries or manipulating existing session states to trigger the erroneous memory access condition. Once triggered, the server may respond in a way that reveals the contents of the out-of-bounds memory region, either directly through malformed responses or indirectly by causing timing variations or error messages that leak information about the underlying system state. This categorization highlights the risk associated with insider threats and compromised credentials rather than external remote exploitation without prior access.
Mitigation strategies for this vulnerability must focus on both immediate remediation and long-term architectural improvements. The primary defense is to apply vendor-provided patches or updates that address the specific memory management flaw in the DNS server software. These updates typically involve rigorous input validation, bounds checking before any array or buffer access, and the use of safer programming constructs that prevent pointer arithmetic errors. Additionally, organizations should implement strict least-privilege principles for user accounts interacting with the DNS infrastructure to minimize the attack surface available to potential insiders. Network segmentation can also help isolate critical DNS servers from less trusted network zones, reducing the likelihood of an attacker gaining the necessary authorized access required to trigger this vulnerability.
Furthermore, adopting memory-safe programming languages or employing static and dynamic analysis tools during software development life cycles can prevent such vulnerabilities from being introduced in future versions. Tools that perform fuzzing against DNS parsers are particularly effective at identifying out-of-bounds read conditions before deployment. Monitoring for unusual patterns of DNS queries, especially those involving large payloads or specific query types known to trigger complex parsing logic, can also aid in early detection and response. By combining technical patches with robust access controls and continuous monitoring, organizations can significantly reduce the risk associated with this class of memory safety vulnerabilities in their critical network infrastructure.