CVE-2026-83838 in Windows
Summary
by MITRE • 10/14/2026
Integer underflow (wrap or wraparound) in Windows Bluetooth A2DP driver allows an authorized attacker to elevate privileges over an adjacent network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves a critical integer underflow within the Advanced Audio Distribution Profile implementation of the Microsoft Windows Bluetooth stack, specifically affecting the audio streaming subsystem known as A2DP. This flaw arises from improper handling of numerical values during memory allocation or buffer size calculations, where an arithmetic operation results in a negative value that is subsequently interpreted as a large positive unsigned integer due to type conversion rules inherent in C and C++ programming languages commonly used in system drivers. Because the Bluetooth stack operates with high privileges within the operating kernel space, this miscalculation can lead to severe memory corruption issues when the driver attempts to allocate or access buffers based on these erroneous size parameters. The presence of an adjacent network requirement indicates that the attack vector is local but requires physical proximity, allowing a threat actor who has already gained authorized access to the system and is within Bluetooth range to exploit this condition without needing remote code execution capabilities over the internet.
From a technical perspective, integer underflows in driver-level components are particularly dangerous because they often bypass standard boundary checks that rely on signed comparisons while using unsigned arithmetic for actual memory operations. When an attacker can trigger this underflow through crafted Bluetooth packets or specific pairing sequences, it may result in heap corruption, stack overflow, or arbitrary write primitives depending on the exact context of the allocation and subsequent usage of the buffer. This type of flaw is classically categorized under CWE-192 Integer Underflow which leads to a weakness that can be leveraged for privilege escalation if the vulnerable code executes with elevated system rights. The impact extends beyond simple denial of service, as successful exploitation typically allows an attacker to execute arbitrary code in kernel mode, thereby gaining full control over the affected Windows operating system and potentially pivoting to other systems on the local network segment.
The operational impact of this vulnerability is significant for any organization relying on Bluetooth connectivity for peripherals or file transfers while maintaining strict security postures regarding privilege separation. An adversary who exploits this flaw can bypass user-level access controls, install malware with persistent administrative privileges, exfiltrate sensitive data stored locally, and disable security software that relies on kernel integrity checks. Furthermore, because the vulnerability is tied to a specific driver component responsible for audio streaming, it may remain undetected by standard endpoint detection systems if the exploitation does not trigger obvious system crashes or performance anomalies immediately after execution. The requirement for an adjacent network means that physical access or proximity remains a prerequisite, which limits the attack surface compared to remote vulnerabilities but increases the risk in environments where untrusted devices are frequently paired with corporate laptops or workstations.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. Organizations should prioritize applying the latest security updates provided by Microsoft for their Windows operating systems, as these patches typically include code hardening measures that validate input sizes before performing arithmetic operations or use safe integer libraries to prevent wraparound conditions. Additionally, implementing strict Bluetooth device whitelisting policies can reduce the attack surface by preventing unauthorized devices from establishing connections with vulnerable endpoints. Security teams should also monitor for unusual kernel-level activity and privilege escalation attempts using endpoint detection and response tools configured to alert on anomalies in driver behavior or unexpected changes in process token privileges. Regular audits of peripheral connectivity settings and disabling Bluetooth when not in use further reduce the likelihood of exploitation by limiting the availability of the attack vector.