Description

Origin validation error in Windows Network Address Translation (NAT) allows an unauthorized attacker to perform spoofing over an adjacent network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.3",
  "pubDate": "2026-08-11T17:18:04.363Z",
  "pubdate": "2026-08-11T17:18:04.363Z",
  "executiveSummary": "An origin validation vulnerability exists within the Windows Network Address Translation (NAT) component, allowing an unauthorized threat actor to execute spoofing attacks over an adjacent network.\nThe primary impact of this security flaw includes unauthorized traffic manipulation, potential interception of network communications, and spoofing capabilities that compromise network integrity.\nThe affected system is the Windows Network Address Translation (NAT) service across supported deployments.\nThe risk implications are significant for enterprise and localized environments where adjacent network trust assumptions are exploited, potentially facilitating man-in-the-middle conditions or unauthorized data injection.\nAttacker capabilities require positioning on the adjacent local network to interact directly with the vulnerable NAT implementation.\nExploitation requirements include network adjacency to the target victim or gateway, enabling the transmission of crafted packets designed to bypass insufficient origin checks.",
  "technicalDetails": "The vulnerability stems from an origin validation error within the packet processing and state tracking mechanisms of the Windows Network Address Translation (NAT) driver and associated routing components.\nThe vulnerable component fails to properly verify the cryptographic or logical origin of incoming network packets mapped through the NAT translation tables.\nBecause strict source validation and ingress filtering checks are inadequately enforced during packet decapsulation and address translation routines, an attacker can forge packet headers.\nThe attack flow proceeds as follows: First, the unauthorized threat actor situated on the adjacent network crafts specialized packets with manipulated source identifiers or routing metadata.\nSecond, these crafted packets are transmitted toward the vulnerable Windows NAT instance.\nThird, due to the absence of robust origin validation, the Windows NAT component incorrectly processes, translates, and forwards the spoofed packets, treating them as legitimate traffic originating from trusted internal or external endpoints.\nAuthentication requirements are nonexistent; the attacker requires no credentials to transmit these packets over the local physical or logical medium.\nPrivilege requirements are minimal, as standard network access to the adjacent broadcast or collision domain is sufficient to interact with the network stack.\nNetwork exposure is restricted to the adjacent network boundary, meaning the attacker must be locally connected via Ethernet, Wi-Fi, or bridged virtual interfaces to reach the NAT interface.\nPost-exploitation impact involves the ability to spoof network communications, disrupt established sessions, inject unauthorized data streams into active connections, or mislead network monitoring solutions relying on NAT translation logs."
}