CVE-2026-62878 in Windows
Summary
by MITRE • 08/11/2026
Stack-based buffer overflow in Windows DNS allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a critical stack-based buffer overflow flaw within the Windows Domain Name System implementation that enables remote code execution by unauthenticated attackers. The vulnerability occurs when the dns.exe process fails to properly validate input parameters during DNS query processing, specifically when handling malformed resource record data structures. Attackers can craft specially crafted DNS packets containing oversized or improperly formatted data that overflows the allocated stack buffer, potentially allowing arbitrary code execution with the privileges of the dns.exe process. This flaw exists at the protocol parsing layer where insufficient bounds checking permits memory corruption that can be exploited to overwrite critical program execution pointers and control flow registers.
The technical exploitation leverages fundamental weaknesses in input validation mechanisms that should have been implemented according to established security principles outlined in CWE-121 Stack-based Buffer Overflow. The vulnerability demonstrates characteristics consistent with attack patterns described in the MITRE ATT&CK framework under T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, where attackers can establish remote code execution through network-based attacks against system services. The Windows DNS service operates with elevated privileges typically corresponding to the local system account, making successful exploitation particularly dangerous as it could provide attackers with complete system compromise capabilities.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential denial of service conditions and lateral movement within network environments where DNS servers serve as critical infrastructure components. Organizations relying on Windows DNS for domain resolution face significant risk exposure since the attack vector requires no authentication credentials and can be executed entirely over the network. The vulnerability affects multiple Windows Server versions including 2012, 2016, 2019, and 2022, with the specific flaw residing in the DNS server's handling of certain record types during query processing. Network traffic analysis reveals that exploitation typically involves sending malformed dns packets containing oversized resource records that trigger the buffer overflow condition.
Mitigation strategies should prioritize immediate patch deployment through Microsoft security updates which address the underlying input validation deficiencies in the dns.exe component. Organizations should implement network segmentation and access controls to limit exposure of DNS servers to untrusted networks, utilizing firewall rules to restrict dns query traffic to authorized clients only. Additional protective measures include monitoring for anomalous dns traffic patterns that might indicate exploitation attempts, implementing intrusion detection systems capable of identifying malformed dns packets, and maintaining regular backup copies of dns server configurations to facilitate rapid recovery should exploitation occur. Security teams must also consider disabling unnecessary dns server features and services to reduce the overall attack surface, aligning with defense-in-depth principles recommended by nist cybersecurity framework and iso 27001 standards for information security management.