CVE-2026-97831 in Windows
Summary
by MITRE • 10/14/2026
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 • 10/14/2026
The vulnerability described constitutes a critical security flaw within the Domain Name System (DNS) server infrastructure, specifically categorized 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 structure. In the context of DNS servers, which are fundamental components of internet routing and resolution, such flaws can have severe implications for system stability and information confidentiality. The specific nature of this vulnerability allows an attacker who has already established authorized network access to exploit the improper memory handling logic within the server's processing routines. By crafting a specially designed query or packet that triggers the erroneous boundary check failure, the attacker forces the DNS service to read from adjacent memory regions that were not intended for public disclosure.
From a technical perspective, out-of-bounds reads are often precursors to more severe exploits such as remote code execution, but in this instance, the primary impact is information disclosure. When the server processes maliciously formatted requests, it may leak sensitive data stored in neighboring memory locations. This leaked data can include internal network topology details, cached DNS records containing private domain names and IP addresses, authentication tokens, or even parts of other users' queries if multi-tenant architectures are employed. The ability to read arbitrary memory contents undermines the integrity and confidentiality guarantees expected from enterprise-grade DNS services. Because the attack requires authorized access, it typically targets internal networks where an attacker has already compromised a host with legitimate credentials, making this a post-exploitation technique that facilitates lateral movement or deeper reconnaissance within the protected environment.
The operational impact of this vulnerability is significant for organizations relying on their own infrastructure for name resolution rather than external public resolvers. An adversary leveraging this flaw can map internal network structures without triggering traditional intrusion detection systems that focus on malicious payloads like shellcode. The disclosure of cached DNS data reveals which services are running, what subdomains exist, and potentially sensitive business logic embedded in hostnames or IP assignments. This information is invaluable for planning further attacks against specific applications or services hosted within the organization. Furthermore, if the leaked memory contains cryptographic keys or session tokens, the attacker could impersonate legitimate users or decrypt communications, leading to a complete compromise of confidentiality and integrity for affected systems.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary defense is applying vendor-provided patches that correct the buffer boundary checks within the DNS server software. Organizations should prioritize updating their internal DNS infrastructure as soon as these security updates are available, ensuring that all nodes in a distributed DNS environment are consistently patched to prevent exploitation across any entry point. In addition to patching, network segmentation plays a crucial role in limiting the blast radius of such vulnerabilities. By restricting which hosts can query internal DNS servers and implementing strict access control lists, organizations reduce the attack surface for authorized attackers who might attempt to exploit this flaw. Deploying intrusion prevention systems that detect anomalous DNS traffic patterns associated with memory corruption attempts can also provide an additional layer of defense.
From a classification standpoint, this vulnerability aligns closely with CWE-125, which defines out-of-bounds read vulnerabilities where software reads data past the end or before the beginning of the intended buffer. It is also relevant to CWE-200, concerning exposure of sensitive information to an unauthorized actor. In terms of offensive security frameworks like MITRE ATT&CK, this behavior corresponds to techniques such as T1087, which involves account discovery through local system queries, and potentially T1537 if the data exfiltration is used to transfer stolen DNS cache data out of the network. Understanding these mappings helps security teams align their detection rules with known adversary behaviors. Continuous monitoring for unusual memory usage patterns or unexpected responses from DNS services can aid in identifying potential exploitation attempts before significant damage occurs, ensuring that the confidentiality and availability of critical naming infrastructure remain intact against sophisticated internal threats.