Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessReach Windows WLAN service over network
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DeliverySend crafted WLAN frame
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ExploitTrigger CWE-191 integer underflow
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ExecutionCrash or hang WLAN service
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ImpactDeny wireless/network availability
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Integer underflow checks
|
| Exploitation Conditions | The target must be running the Windows WLAN (wireless LAN) Service on an affected, unpatched build (e.g., Windows 11 24H2 <10.0.26100.9711 or Windows Server 2025 <10.0.26100.33650). Per the CVSS vector (PR:N/UI:N), no authentication or user interaction is required and exploitation works against default configurations where the WLAN service is active. The practical limiting factor is reachability: despite the AV:N rating, this is a wireless-networking component, so attackers likely need link-local/adjacent access to the WLAN stack rather than arbitrary internet routing, and the impact is bounded to denial of service - no confidentiality or integrity compromise. |
| Impact | This is a moderate-priority availability flaw whose signals are consistent but unremarkable. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N) describes a remote, low-complexity, unauthenticated path, but impact is confined to availability (C:N/I:N/A:H) - a denial of service only, with no data exposure or code execution. The 7.5 base score is driven entirely by that single A:H impact, so the 'High' severity should not be read as code-execution risk. SSVC corroborates a lower operational urgency: Exploitation=none (no observed or public exploitation), Technical Impact=partial, and only Automatable=yes raises a mild flag that a working exploit could be scripted broadly. No EPSS score was provided, and there is no CISA KEV listing and no POC in the supplied data, so exploitation status is 'no public exploit identified at time of analysis.' One signal worth verifying: the product is the Windows WLAN (wireless LAN) Service, which typically implies an adjacent/link-local attacker (AV:A), yet Microsoft rated it AV:N (network) - confirm the true reachability with the vendor, as adjacency would further limit real-world exposure. Net: a legitimate patch-worthy DoS, but not an emergency relative to RCE-class Windows bugs. |
| Exploit ScenarioDerived | An unauthenticated attacker within reach of a target's wireless networking stack sends a specially crafted WLAN frame or packet that triggers an integer underflow (CWE-191) in the Windows WLAN Service. The miscalculated length/size value leads to a crash or resource exhaustion, taking down wireless connectivity or the service on the host. No public exploit code is identified at time of analysis, and the impact is denial of service only - no code execution or data disclosure. |
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Alert meAnalysisAIv1 – Oct 14, 2026
Denial of service in the Windows WLAN Service affects Windows 11 builds 23H2 through 26H2 and Windows Server 2025, where an integer underflow in the wireless networking component can be triggered by an unauthenticated attacker to exhaust or crash the service. Per the assessed CVSS vector (AV:N/AC:L/PR:N/UI:N, C:N/I:N/A:H), no credentials or user interaction are required and the sole impact is loss of availability, with the practical gating factor being reachability of the WLAN stack rather than direct internet exposure; no public exploit code has been identified at time of analysis, CISA SSVC records Exploitation: none, and vendor patches are available. CISA's SSVC also flags the issue as Automatable: yes with partial technical impact, making it a moderate-priority patching item for wireless-capable endpoints and servers.
RemediationAI
Patch status: Patch available per vendor advisory - apply the Microsoft security update listed in the MSRC update guide for CVE-2026-83855 (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83855) to move affected systems to or above the fixed builds: Windows 11 23H2 10.0.22631.7652, Windows 11 24H2 and Windows Server 2025 10.0.26100.9711 / 10.0.26100.33650, Windows 11 25H2 10.0.26200.9711, Windows 11 26H1 10.0.28000.3231, and Windows 11 26H2 10.0.26300.9711. Where immediate patching is not possible, a compensating control is to stop and disable the WLAN AutoConfig service (WlanSvc) and, where applicable, the WLAN service on hosts that do not need Wi-Fi - the trade-off is complete loss of wireless connectivity and any dependent location/Wi-Fi Direct features. Lower-impact hardening includes temporarily removing or disabling wireless network adapters on servers (Windows Server 2025 is only affected where a wireless stack is present), constraining wireless coverage and using strong WPA3/802.1X authentication to limit which clients can reach the WLAN stack, and isolating untrusted wireless segments so adjacent attackers cannot reach management or infrastructure hosts over the air. Because SSVC marks the flaw as Automatable: yes but Exploitation: none, these controls should be treated as temporary until the build-level updates above are deployed.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 7 packages in euvd
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Technical ContextAI · show details
The root cause is CWE-191, integer underflow (wrap or wraparound), inside the Windows WLAN Service - the user-mode component behind WlanSvc/WLAN AutoConfig that parses 802.11 management and connection-related data. An underflow occurs when a length, offset, or counter is computed by subtracting a larger value from a smaller one in an unsigned context, wrapping to a very large number that is then used in a size calculation, loop bound, or buffer operation; the resulting memory-safety or resource-exhaustion condition removes the service's ability to respond, producing denial of service. Because the flaw lives in the wireless networking path, the affected surface is the WLAN protocol handling rather than a standard TCP service, and the assessed vector (PR:N/UI:N) confirms the trigger requires neither authentication nor user interaction against default configurations where the WLAN service is running. Note that the source tags include 'Authentication Bypass', which is not corroborated by the CVSS vector (C:N/I:N) or by SSVC's partial technical impact; the authoritative assessment is availability-only, so this should be triaged as a DoS rather than a credential or access-control bypass.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Unauthenticated, low-complexity network-reachable integer underflow with no user interaction; impact is availability-only (A:H), with C:N/I:N as it is a pure DoS.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Integer underflow (wrap or wraparound) in Windows WLAN Service allows an unauthorized attacker to deny service over a network.
Executive ViewAI
A high-severity denial-of-service flaw in the Windows WLAN Service exposes Windows 11 builds 23H2 through 26H2 and Windows Server 2025 to unauthenticated attackers capable of crashing or exhausting the wireless networking service, causing loss of Wi-Fi connectivity on affected machines. Because these builds cover the majority of the organization's current Windows endpoint estate, the practical exposure is a fleet-wide availability risk to wireless-dependent operations - mobile and remote workers, clinical or retail floor staff, warehouse scanning devices, and any server relying on wireless or WLAN-adjacent services - rather than an isolated defect on a niche system. No public exploit code has been identified at time of analysis and vendor patches are available, so leadership should treat this as an expedited, well-understood patching obligation rather than an emergency, while recognizing that an automatable unauthenticated availability flaw can still produce disruptive, repeatable outages once tooling matures.
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Threat Intelligence Overview
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
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EUVD-2026-99391
GHSA-86rh-fwj4-9gwg
NVD
CVE.org
EPSS
Vulnrichment
Exploit-DB