Researcher: a vulnerability affecting iOS 13.3.1 and later prevents VPNs from encrypting some traffic, potentially exposing user data or leaking IP addresses
A currently unpatched security vulnerability affecting iOS 13.3.1 or later prevents virtual private network (VPNs) …
Context & Ripple Effects
iOS has a recurring record of traffic-interception flaws: a critical HTTPS bug in 2015 exposed some 25,000 iOS apps to eavesdropping, and in 2017 a researcher found 76 popular iOS apps, including VICE News, vulnerable to interception of TLS-protected data. VPN-specific leaks followed a parallel track, with some providers found leaking IP addresses via the WebRTC bug in 2018.
The new report moves the problem down the stack: rather than an app or a browser leaking, the researcher says iOS 13.3.1 and later itself prevents VPNs from encrypting some traffic, with ProtonVPN first publicizing the issue. If the OS network layer can bypass the tunnel, the core promise of every VPN on the platform is conditional on Apple's routing behavior.
First-order effects
- Users on iOS 13.3.1 or later who rely on VPNs face unpatched exposure: some traffic can leave the device unencrypted and IP addresses can leak, defeating the privacy the subscription is paying for.
- VPN providers on iOS — ProtonVPN most visibly — must now disclose a limitation rooted in the operating system, one they cannot fix in their own apps.
Second-order effects
- Apple is under pressure to patch the routing behavior, and until it does, VPN vendors' competitive claims about encryption coverage are constrained by what iOS permits.
- The WebRTC precedent suggests buyers will demand leak-testing of VPN configurations per OS version, shifting assurance work from providers' marketing to independent audits of platform behavior.
Third-order effects
- The pattern across the 2015 HTTPS bug, the 2017 app-interception findings, and this tunnel bypass points to a structural rule: privacy guarantees on a closed mobile OS are only as strong as the vendor's network stack, and users cannot verify it from the app layer.
- If OS-level bypasses keep surfacing, VPN trust may consolidate around platforms and providers that submit to external verification of traffic routing, not just encryption claims.
The trend: VPN privacy is increasingly bounded by the underlying OS network stack, pushing the industry from encryption marketing toward independently verified traffic-routing guarantees.