CVE-2026-97840 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 services, such flaws can have severe implications for system stability and information confidentiality. The specific nature of this vulnerability allows an authorized attacker, meaning someone who has valid credentials to interact with the DNS service, to exploit this memory mismanagement issue during the processing of network requests or responses.
From a technical perspective, out-of-bounds reads typically arise due to insufficient validation of input parameters or incorrect calculation of buffer lengths by the application logic. When the DNS server processes specific malformed or carefully crafted packets that trigger this condition, it may read adjacent memory contents that were not intended for disclosure. This can lead to the leakage of sensitive internal data structures, such as authentication tokens, private keys, cached query results containing proprietary domain information, or even parts of the operating system's kernel memory if the server runs with elevated privileges. The attacker leverages this discrepancy in memory access control to extract information that would otherwise remain isolated within the secure execution environment of the DNS service process.
The operational impact of this vulnerability is primarily centered on confidentiality and potentially availability. While the primary outcome is the disclosure of sensitive information, which compromises the integrity of the organization's network architecture by revealing internal topology or security configurations, it can also lead to denial-of-service conditions if the memory corruption causes the server process to crash or behave unpredictably. For organizations relying on high-availability DNS services, such instability can disrupt critical business operations that depend on consistent name resolution. Furthermore, the disclosed information could serve as a stepping stone for more sophisticated attacks, including privilege escalation or further network infiltration, thereby amplifying the risk profile significantly beyond the initial memory error.
In terms of industry standard classifications, this vulnerability aligns with CWE-125, which defines out-of-bounds read vulnerabilities where software reads data past the end, or before the beginning, of a buffer. It also relates to CWE-200, which covers exposure of sensitive information to an unauthorized actor. From a tactical perspective within the MITRE ATT&CK framework, this behavior is consistent with techniques used in reconnaissance and collection phases, such as T1537 (Transfer Data to Cloud Account) if the data is exfiltrated externally, or more broadly under initial access vectors that leverage valid credentials to probe for internal secrets. The presence of an authorization requirement indicates that the attack surface is limited to authenticated users, which reduces the likelihood of remote unauthenticated exploitation but does not eliminate the risk from insider threats or compromised accounts.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The most effective solution involves applying vendor-provided patches that address the specific memory handling logic within the DNS server software. These updates typically include bounds checking mechanisms to ensure that all buffer accesses remain within allocated limits, thereby preventing the read operation from reaching unauthorized memory regions. Additionally, organizations should enforce strict least-privilege principles for accounts interacting with the DNS service, ensuring that only essential services and administrators have access rights. Implementing network segmentation can also limit the blast radius by isolating DNS servers in dedicated zones where lateral movement is restricted. Regular security audits and static code analysis tools designed to detect memory safety issues should be integrated into the development lifecycle to prevent similar vulnerabilities from being introduced in future software versions.