iOS Vulnerability Prevents VPNs From Encrypting All Traffic

A vulnerability affecting iOS 13.3.1 and later prevents virtual private networks (VPNs) from encrypting all traffic, allowing some internet connections to bypass encryption, potentially exposing users' data and IP addresses.

ios device network ip wireshark

A screenshot from ProtonVPN demonstrating exposed connections to Apple's servers that should be protected by the VPN

Details on the vulnerability were shared today by Bleeping Computer after it was discovered by ProtonVPN. The vulnerability is caused because iOS isn't terminating all existing connections when a user connects to a VPN, allowing them to reconnect to destination servers once the VPN tunnel has been established.

Connections made after connecting to a VPN on an iOS are not affected by this bug, but all previously established connections are not secure. This could potentially lead to a user who believes they are protected accidentally exposing IP an address and therefore, an approximate location.

Apple's Push Notifications are cited as an example of a process using connections on Apple's servers that aren't closed automatically when connecting to a VPN, but it can affect any app or service running on a user's device.

VPNs cannot work around the issue because iOS does not allow VPN apps to kill existing network connections, so this is a fix that will need to be implemented by Apple. Apple is aware of the vulnerability and is looking into options to mitigate it.

Until fixed, VPN users can connect to a VPN server, turn on Airplane Mode and then turn off Airplane Mode to kill all existing connections. The mitigation isn't entirely reliable, however, so iPhone and iPad owners who rely on VPNs should be careful until Apple puts out a fix.

Popular Stories

Apple CarPlay Ultra instrument cluster themes 01

Apple's 'CarPlay Ultra' Experience Now Available

Thursday May 15, 2025 5:07 am PDT by
Apple today announced that its next-generation CarPlay experience, now dubbed "CarPlay Ultra" begins rolling out today, starting with Aston Martin vehicles. Subscribe to the MacRumors YouTube channel for more videos. CarPlay Ultra is now available with new Aston Martin vehicle orders in the U.S. and Canada. It will also be available for existing models that feature the brand's next-generation ...
Apple CarPlay Ultra instrument cluster themes 01

Apple's CarPlay Ultra Is Here – Does Your iPhone Support It?

Thursday May 15, 2025 5:17 am PDT by
Apple's recently announced CarPlay Ultra promises a deeply integrated in-car experience, but not all iPhone users will be able to take advantage of the new feature. According to Apple's press release, CarPlay Ultra requires an iPhone 12 or later running iOS 18.5 or later. This means if you're using an iPhone 11, iPhone XR, or any older model, you'll need to upgrade your device to access...
iOS 18

Apple Releases iOS 18.5 With New Wallpaper, Screen Time Changes, Carrier Satellite Support for iPhone 13 and More

Monday May 12, 2025 10:06 am PDT by
Apple today released iOS 18.5 and iPadOS 18.5, the fifth updates to the iOS 18 and iPadOS 18 operating systems that came out last September. iOS 18.5 and iPadOS 18.5 come a little over a month after Apple released iOS 18.4 and iPadOS 18.4. The new software can be downloaded on eligible iPhones and iPads over-the-air by going to Settings > General > Software Update. The iOS 18.5 update has a...
iPhone 12 Made in India

Trump Tells Tim Cook to Stop Building iPhones in India

Thursday May 15, 2025 2:21 am PDT by
President Donald Trump has asked Apple CEO Tim Cook to halt the company's manufacturing expansion in India, in a potential disruption of Apple's plan to shift iPhone production away from China. "I had a little problem with Tim Cook yesterday," Trump said during his state visit to Qatar, according to Bloomberg. "He is building all over India." "They [India] have offered us a deal where...
CarPlay Ultra Climate Controls

Apple Says These Vehicle Brands Plan to Offer All-New CarPlay Ultra

Thursday May 15, 2025 8:13 am PDT by
Apple today announced the launch of CarPlay Ultra, the long-awaited next-generation version of its CarPlay software system for vehicles. CarPlay Ultra features deep integration with a vehicle's instrument cluster and systems, built-in Radio and Climate apps, customizable widgets, and more. The interface is tailored to each vehicle model and automaker's identity, and drivers can also adjust...
apple music

Apple Music Gets New Transfer Tool to Make Switching From Spotify Easier

Wednesday May 14, 2025 5:17 pm PDT by
Apple this week introduced a new feature designed to allow prospective Apple Music users to import their saved music and playlists from third-party music services to Apple Music. The feature is either in an expanded testing phase or it has started rolling out, and it is available in Australia and New Zealand according to an Apple Support document. Signs of the transfer option first surfaced...
maxresdefault

Here's the First Real-World Look at Apple's CarPlay Ultra

Thursday May 15, 2025 5:52 am PDT by
The first videos of Apple's CarPlay Ultra experience are now available, providing a never-before-seen look at the long-anticipated iPhone-linked infotainment software. British automaker Aston Martin today shared the first video of Apple's CarPlay Ultra experience in-action, followed by a detailed walk-through of the CarPlay Ultra system on Top Gear's YouTube channel, which provides the...

Top Rated Comments

Will Tisdale ? Avatar
67 months ago

This is 100% fake and not a bug. All VPNs, such as those on the desktop, do this by default unless specifically configured, as to not interrupt ongoing downloads, or worse, cause UDP-based services to silently fail.
I don’t think so.
iOS used to handle this correctly, then stopped.
Not tearing down existing connections completely undermines the point of a VPN.
Score: 11 Votes (Like | Disagree)
Will Tisdale ? Avatar
67 months ago

Nope. I have two full tunnels on two different clients (Cisco Anyconnect, and Pulse Secure)
Well, I can tell you that Anyconnect will tear down any active connections, assuming it’s configured correctly. My work VPN certainly does.

TCP is designed to retry after being torn down. It’s no biggie.

The fact is, this is an iOS bug, which was introduced recently.
Score: 5 Votes (Like | Disagree)
konqerror Avatar
67 months ago
This is 100% fake and not a bug. All VPNs, such as those on the desktop, do this by default unless specifically configured, as to not interrupt ongoing downloads, or worse, cause UDP-based services to silently fail. Windows built-in VPN client has this exact same behavior.
Score: 3 Votes (Like | Disagree)
Westside guy Avatar
67 months ago
I’m sometimes stunned by the upvotes people get for posting incorrect information.

If a VPN is configured to send all network traffic through the VPN when it’s running - which is typically what‘s done - then all traffic should be routing through it from the moment it’s enabled. Not just connections to new end points established afterward - all traffic.

Even if a VPN is configured to just carry traffic to a few specific end points (such as the OpenVPN tunnel to our servers, which I’m relying on heavily right now due to the stay at home order currently in place here in Washington): if you’re already connected to one of those end points before establishing the tunnel, you would expect all further traffic to go through the tunnel. The idea that you wouldn’t is ludicrous.
Score: 3 Votes (Like | Disagree)
Will Tisdale ? Avatar
67 months ago

I feel like we need more info here.

As others have said, it would be problematic to silently kill existing connections when connecting to a VPN. That's certainly not the behavior I would expect. I suppose it depends on whether you use a VPN to add certain networks (such as your corporate office), or to globally route all your traffic (such as for privacy reasons). In the former case, I don't want my non-office connections to be reset.

If MacRumors is reporting this right and VPN apps cannot reset connections, that makes me wonder what changed here. Did iOS previously indeed terminate any open socket when connecting?
I feel that people need to learn about the expected behaviour of VPNs before commenting.
There’s actually two types on iOS. Split vpn and full tunnel. Split allows some stuff to be routed elsewhere. Full tunnel tunnels everything.
Score: 3 Votes (Like | Disagree)
Square-Eyes Avatar
67 months ago
I got caught out by the fact that if you tether a device to your phone it will bypass the phone’s VPN ??‍♂️
Score: 2 Votes (Like | Disagree)