TunnelVision: Decloaking VPNs Using DHCP

Published Date: December 28, 2024

Package Affected Versions Patched Versions Severity
📦 quincy (Rust) <= 0.13.0 Moderate

Description

Vulnerability Details


A flaw affects nearly all VPN implementations, allowing attackers to exploit DHCP option 121. By injecting entries into routing tables, attackers can redirect traffic meant to pass securely through a VPN. Instead, traffic flows through the local network interface, bypassing encryption entirely.

In short: your VPN might not be as private as you think.




Impact


Every VPN user is potentially at risk. This vulnerability isn’t limited to a single VPN type or vendor—it’s a systemic weakness.

Patches & Workarounds

Workarounds


Disable DHCP option 121 in your DHCP client configuration. This prevents routing table injections via DHCP.

While not a perfect fix, it reduces exposure until a proper patch is available.




Recommendation



  • Disable DHCP option 121 in your network settings.

  • Monitor the Quincy repository for updates.

  • Avoid using public or untrusted networks until a patch is released.

References

https://www.leviathansecurity.com/blog/tunnelvision
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