CVE-2026-83855 in Windows
Summary
by MITRE • 10/14/2026
Integer underflow (wrap or wraparound) in Windows WLAN Service allows an unauthorized attacker to deny service over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified involves a critical integer underflow within the Windows Wireless LAN Service, specifically affecting how memory buffers are allocated and managed during packet processing operations. This flaw stems from improper validation of input values provided by remote attackers or maliciously crafted wireless frames. When an attacker sends specially constructed data packets to the affected system, the service fails to correctly account for negative results when performing arithmetic calculations on buffer sizes or offsets. Instead of rejecting the invalid request, the system interprets the underflowed value as a large positive integer due to standard two's complement representation rules in computing systems. This misinterpretation leads to an allocation of insufficient memory space relative to what is actually required by the incoming data stream.
The operational impact of this vulnerability centers on service denial and potential remote code execution, although the primary classification highlights denial of service capabilities. By triggering the integer underflow, an attacker can cause the WLAN service to write beyond the bounds of allocated buffers or crash due to invalid memory access patterns. This results in a complete disruption of wireless connectivity for the host machine. In more severe scenarios where heap corruption occurs, it may allow for arbitrary code execution with the privileges of the local security authority, effectively granting full control over the compromised system. The attack vector is typically network-based, requiring proximity to the victim's wireless access point or direct connection within a trusted LAN segment if authentication bypasses are exploited alongside this flaw.
From a technical standards perspective, this vulnerability aligns closely with CWE-192, which defines integer coercion errors leading to buffer overflows or underflows. It also maps to ATT&CK technique T1498, Network Denial of Service, as the primary observable effect is the degradation or cessation of network services on the target host. The root cause lies in insufficient boundary checks during data parsing routines within the WLAN service architecture. Developers failed to verify that arithmetic operations involving user-controlled inputs would not result in values outside the expected positive range before proceeding with memory allocation and copy operations.
Mitigation strategies must prioritize immediate patching through official Microsoft security updates, which address these specific validation gaps by enforcing strict type checking and range verification for all integer calculations related to buffer management. Administrators should ensure that Windows Update policies are configured to automatically apply critical security patches as soon as they become available. Additionally, network segmentation can reduce the attack surface by isolating wireless infrastructure from sensitive internal networks. Implementing intrusion detection systems capable of identifying malformed packets or anomalous traffic patterns associated with integer overflow exploits provides an additional layer of defense. Regular auditing of system logs for service crashes related to wlansvc.exe can help in early detection and response to attempted exploitation activities.