CVE-2026-97838 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 categorized as an out-of-bounds read error. This type of memory safety issue arises 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 presence of this vulnerability indicates a failure in proper bounds checking during the processing of specific DNS queries or responses, allowing the application to read memory contents that were not intended to be accessed by the current execution context.
From a technical perspective, an out-of-bounds read typically occurs when input validation mechanisms fail to verify that data indices or lengths are within acceptable limits before accessing memory regions. When a malicious actor sends crafted DNS packets containing specially formatted queries with manipulated length fields or index values, the server may interpret these inputs incorrectly. Instead of rejecting the malformed request, the processing logic proceeds to dereference pointers based on these invalid parameters. This leads to the retrieval of arbitrary data from adjacent memory locations that belong to other processes, internal buffers, or sensitive system structures. The attacker does not need to execute code directly but can leverage this information leak to gather intelligence about the server's environment, potentially including stack addresses, heap layouts, or credentials stored in nearby memory blocks.
The operational impact of this vulnerability is primarily centered on unauthorized information disclosure rather than immediate remote code execution or denial of service, although secondary impacts such as system instability are possible if the read operation triggers a segmentation fault or exception handling routine that disrupts normal operations. For an authorized attacker, who may have legitimate access to query the DNS server but lacks elevated privileges for other sensitive functions, this flaw provides a pathway to bypass security controls through side-channel information gathering. The disclosed data can be used as stepping stones in more complex attack chains, such as defeating address space layout randomization (ASLR) or identifying valid memory addresses for subsequent exploitation attempts. This significantly lowers the barrier for further compromise of the DNS infrastructure and potentially other services running on the same host.
In terms of industry standards, this vulnerability aligns with Common Weakness Enumeration identifier CWE-125, which defines out-of-bounds read errors as a distinct category of memory safety vulnerabilities. It also relates to ATT&CK technique T1005, known as Data from Local System, where adversaries seek to collect data stored on local systems for later exfiltration or analysis. The exploitation vector is classified under network-based attacks, requiring the attacker to have some level of authorized access to interact with the DNS service, which distinguishes it from purely remote unauthenticated exploits but still poses a significant risk due to the critical nature of DNS services in most enterprise and public-facing environments.
Mitigation strategies for this vulnerability must focus on both immediate remediation and long-term architectural improvements. The primary defense is the application of vendor-provided patches or updates that address the specific memory handling logic within the DNS server software. These updates typically involve implementing rigorous input validation to ensure that all indices, lengths, and offsets are strictly checked against buffer boundaries before any memory access occurs. Additionally, developers should employ static analysis tools and fuzzing techniques during the software development lifecycle to detect such boundary violations early. For system administrators, ensuring that the DNS server operates with minimal privileges can limit the scope of data accessible if an exploit is successful. Furthermore, deploying network segmentation policies restricts which clients can query the DNS server, thereby reducing the attack surface available to potential adversaries who might attempt to leverage this information disclosure vulnerability for further reconnaissance or lateral movement within the network infrastructure.