Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAuthenticate as low-privilege local user
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DeliveryInvoke vulnerable RRAS operation
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ExploitWin use-after-free race window
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ExecutionReclaim freed object with controlled data
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ImpactExecute code as SYSTEM
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires that the Routing and Remote Access Service (RRAS) role/feature is installed and running on the target Windows host - RRAS is not enabled by default on client or server SKUs, so hosts configured as VPN/NAT/routing gateways are the realistic targets. The attacker must additionally have valid local authenticated access with at least low privileges (PR:L) and the ability to execute code or interact with the service locally (AV:L); there is no remote or unauthenticated path. Realistic exploitation is further limited by high attack complexity (AC:H): the use-after-free is a race condition requiring the attacker to reliably win a timing window and reclaim the freed object, which SSVC assesses as not automatable. These factors - RRAS being a non-default role, mandatory local authentication, and race-dependent exploitation - meaningfully constrain real-world risk below what the 7.0 score alone implies. |
| Impact | This is a moderate-priority, not emergency, vulnerability. The CVSS 3.1 base score of 7.0 (High) is tempered by its vector: AV:L means no remote reachability - the attacker must already execute code on the host; AC:H reflects the race-condition nature of a use-after-free (CWE-416), which is non-deterministic and often requires precise timing to win; PR:L confirms the attacker must already be an authenticated (low-privilege) local user. The SSVC decision framework reinforces a lower real-world urgency: Exploitation = none (no observed activity), Automatable = no (consistent with AC:H, not a point-and-click mass-exploitation primitive), though Technical Impact = total aligns with the C:H/I:H/A:H full-SYSTEM-compromise outcome of a successful privilege escalation. There is no CISA KEV listing and no public exploit identified at time of analysis, so this is a high-impact-but-conditional local EoP rather than a widespread, weaponized threat. No signals conflict: CVSS (local, authenticated, high-complexity), SSVC (not automatable, no exploitation), and the absence of KEV/POC all consistently point to a vulnerability worth patching in the normal Patch Tuesday cycle rather than out-of-band. Note the input Tags include 'Denial Of Service' while the description and CVSS (I:H) describe privilege elevation; the UAF could plausibly manifest as either, but the authoritative impact is local EoP. |
| Exploit ScenarioDerived | A low-privileged authenticated user who already has local access to a Windows host running the Routing and Remote Access Service triggers a use-after-free condition in RRAS by exercising a specific operation sequence, winning a timing/race window to reclaim the freed object with attacker-controlled data. Successful exploitation elevates the user to SYSTEM-level privileges, yielding full confidentiality, integrity, and availability impact on the machine. No public exploit code has been identified, and the high attack complexity (AC:H) makes reliable exploitation non-trivial. |
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Alert meAnalysisAIv1 – Oct 14, 2026
Local privilege escalation in the Windows Routing and Remote Access Service (RRAS) stems from a use-after-free memory-safety flaw (CWE-416) that an attacker with low-privileged local access can trigger to gain SYSTEM-level code execution. Real-world exposure is narrow: RRAS is not installed or running by default, so only hosts configured as VPN, NAT, or routing gateways are realistic targets, and exploitation depends on winning a timing race (CVSS AV:L/AC:H/PR:L, high attack complexity), which CISA SSVC assesses as not automatable with no observed exploitation. Microsoft has released a vendor patch, and no public exploit identified at time of analysis - this is a moderate-priority, not emergency, vulnerability whose practical risk sits below what the 7.0 base score alone suggests.
RemediationAI
Vendor-released patch: apply the Microsoft security update for CVE-2026-84020 (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-84020), which raises affected systems to the fixed builds listed per release - 10.0.19044.7807 / 10.0.19045.7807 for Windows 10 21H2/22H2, 10.0.22631.7652 for Windows 11 23H2, 10.0.26100.9711 for Windows 11 24H2, 10.0.26200.9711 for Windows 11 25H2, 10.0.28000.3231 for Windows 11 26H1, 10.0.26300.9711 for Windows 11 26H2, 10.0.20348.5761 for Windows Server 2022, and 10.0.26100.33650 for Windows Server 2025 (including Server Core). Because the attack requires local low-privileged access, prioritize patching RRAS-enabled hosts - VPN, NAT, and routing gateways - and treat general-purpose clients as lower urgency. Where patching must be deferred, the most effective compensating control is to stop or uninstall the Routing and Remote Access Service role on hosts that do not genuinely need it (side effect: any VPN, NAT, or routing gateway function on that host stops working, so verify the role is truly unused before removal), and to restrict interactive logon and RDP to trusted administrators (side effect: reduces the pool of low-privileged accounts that could serve as the attacker's foothold, but does not eliminate risk from local users or compromised accounts). There is no evidence that network-level filtering or port blocking mitigates this issue, since exploitation is entirely local.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 10 packages in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The vulnerability is a use-after-free (CWE-416) in the Windows Routing and Remote Access Service, the component that provides LAN-to-LAN and remote-access VPN, IP routing, and NAT functionality on Windows hosts. The root cause class is a memory-lifetime error: an object is freed while a stale pointer to it is still referenced, so a subsequent access - or heap grooming to reclaim the freed allocation with attacker-controlled data - can corrupt memory and redirect execution under the RRAS service's privileges (typically SYSTEM). Because the bug is reachable only through a local interaction with the service (AV:L) and requires the attacker to reliably hit a timing window and reclaim the freed object (AC:H, independently assessed as not automatable by SSVC), it behaves like a race-condition-driven local privilege escalation rather than a deterministic memory-corruption primitive. Affected CPE coverage spans Windows 10 21H2/22H2, Windows 11 23H2/24H2/25H2/26H1/26H2, Windows Server 2022, and Windows Server 2025 (including Server Core), so the flaw exists across the modern servicing branches even though the RRAS role must be explicitly deployed, and the resulting impact when successfully exploited is total (confidentiality, integrity, and availability all rated High).
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Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local authenticated trigger gives AV:L/PR:L; the use-after-free race condition justifies AC:H; successful SYSTEM elevation yields full C:H/I:H/A:H with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Windows Routing and Remote Access Service (RRAS) allows an authorized attacker to elevate privileges locally.
Executive ViewAI
A memory-safety flaw in Microsoft's Windows Routing and Remote Access Service (RRAS) could allow a low-privileged local user to escalate to full SYSTEM control on affected hosts. Because RRAS is disabled by default and only present on machines configured as VPN, NAT, or routing gateways, the realistic exposure is limited to a small set of network-edge and remote-access systems, which are typically higher-value targets. Leadership should treat this as a scheduled, moderate-priority remediation item rather than an emergency, while confirming that no such gateway hosts remain unaccounted for.
Patch available per vendor advisory. Interim mitigations while patch is scheduled: disable or stop the RRAS service and remove the role where it is not operationally required; restrict local interactive and remote interactive logon on RRAS hosts to a minimal set of trusted administrators to reduce the low-privileged foothold needed for exploitation; and segment or firewall VPN, NAT, and routing gateway hosts to limit lateral movement if SYSTEM-level compromise occurs.
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-2026-99457
GHSA-5rfq-p54c-mw2h
NVD
CVE.org
EPSS
Vulnrichment
Exploit-DB