iOS 16 VPN Tunnels Leak Data, Even When Lockdown Mode Is Enabled

iOS 16 continues to leak data outside an active VPN tunnel, even when Lockdown mode is enabled, security researchers have discovered.

Lockdown Mode Feature
Speaking to MacRumors, security researchers Tommy Mysk and Talal Haj Bakry explained that iOS 16's approach to VPN traffic is the same whether Lockdown mode is enabled or not. The news is significant since iOS has a persistent, unresolved issue with leaking data outside an active VPN tunnel.

In August, it again emerged that third-party VPNs for iOS and iPadOS routinely fail to route all network traffic through a secure tunnel after they have been turned on – an issue that Apple has purportedly known about for years.

Typically, when a user activates a VPN, the operating system closes all existing internet connections and then re-establishes them through the VPN tunnel. In iOS, security researchers have found that sessions and connections established before the VPN is turned on are not terminated as one would expect, and can still send data outside the VPN tunnel while it is active, leaving it potentially unencrypted and exposed to ISPs and other parties.

According to a report from privacy company Proton, an iOS VPN bypass vulnerability had been identified in iOS 13.3.1, which persisted through three subsequent updates. Apple indicated it would add Kill Switch functionality in a future software update that would allow developers to block all existing connections if a VPN tunnel is lost, but this functionality does not appear to prevent data leaks as of iOS 15 and iOS 16.

Mysk and Bakry have now discovered that iOS 16 communicates with select Apple services outside an active VPN tunnel and leaks DNS requests without the user's knowledge:

Mysk and Bakry also investigated whether iOS 16's Lockdown mode takes the necessary steps to fix this issue and funnel all traffic through a VPN when one is enabled, and it appears that the exact same issue persists whether Lockdown mode is enabled or not, particularly with push notifications. This means that the minority of users who are vulnerable to a cyberattack and need to enable Lockdown mode are equally at risk of data leaks outside their active VPN tunnel.

iOS 16 introduced Lockdown mode as an optional security feature designed to protect the "very small number" of users who may be at risk of "highly targeted cyberattacks" from private companies developing state-sponsored spyware, such as journalists, activists, and government employees. Lockdown mode does not enable a VPN itself, and relies on the same third-party VPN apps as the rest of the system.

Due to the fact that iOS 16 leaks data outside the VPN tunnel even where Lockdown mode is enabled, internet service providers, governments, and other organizations may be able to identify users who have a large amount of traffic, potentially highlighting influential individuals. It is possible that Apple does not want a potentially malicious VPN app to collect some kinds of traffic, but seeing as ISPs and governments are then able to do this, even if that is what the user is specifically trying to avoid, it seems likely that this is part of the same VPN problem that affects iOS 16 as a whole.

It is worth noting that Apple only lists high-level features that activate when Lockdown mode is enabled, and Apple has not explicitly mentioned any changes that take place to affect VPN traffic. Nevertheless, as Lockdown mode claims to be an extreme protection measure, it seems like a considerable oversight that VPN traffic is a vulnerable point.

Tag: VPN
Related Forum: iOS 16

Popular Stories

Apple Watch Ultra Night Mode Screen

Apple Watch Ultra 3 Launching Later This Year With Two Key Upgrades

Wednesday July 2, 2025 1:13 pm PDT by
The long wait for an Apple Watch Ultra 3 appears to be nearly over, and it is rumored to feature both satellite connectivity and 5G support. Apple Watch Ultra's existing Night Mode In his latest Power On newsletter, Bloomberg's Mark Gurman said that the Apple Watch Ultra 3 is on track to launch this year with "significant" new features, including satellite connectivity, which would let you...
iPhone 17 Pro in Hand Feature Lowgo

iPhone 17 Pro Coming Soon With These 14 New Features

Friday July 4, 2025 1:05 pm PDT by
Apple's next-generation iPhone 17 Pro and iPhone 17 Pro Max are just over two months away, and there are plenty of rumors about the devices. Below, we recap key changes rumored for the iPhone 17 Pro models. Latest Rumors These rumors surfaced in June and July:Apple logo repositioned: Apple's logo may have a lower position on the back of the iPhone 17 Pro models, compared to previous...
iPhone 17 Pro in Hand Feature Lowgo

iPhone 17 Pro Max Battery Capacity Leaked

Thursday July 3, 2025 5:40 am PDT by
The iPhone 17 Pro Max will feature the biggest ever battery in an iPhone, according to the Weibo leaker known as "Instant Digital." In a new post, the leaker listed the battery capacities of the iPhone 11 Pro Max through to the iPhone 16 Pro Max, and added that the iPhone 17 Pro Max will feature a battery capacity of 5,000mAh: iPhone 11 Pro Max: 3,969mAh iPhone 12 Pro Max: 3,687mAh...
iPhone 17 Pro Lower Logo Magsafe

iPhone 17 Pro's New MagSafe Design Revealed in Leaked Photo

Wednesday July 2, 2025 8:37 am PDT by
The upcoming iPhone 17 Pro and iPhone 17 Pro Max are rumored to have a slightly different MagSafe magnet layout compared to existing iPhone models, and a leaked photo has offered a closer look at the supposed new design. The leaker Majin Bu today shared a photo of alleged MagSafe magnet arrays for third-party iPhone 17 Pro cases. On existing iPhone models with MagSafe, the magnets form a...
airpods pro 2

AirPods Pro 3 to Help Maintain Apple's Place in Earbud Market Amid Increasing Low-Cost Competition

Thursday July 3, 2025 7:25 am PDT by
Apple's position as the dominant force in the global true wireless stereo (TWS) earbud market is expected to continue through 2025, according to Counterpoint Research. The forecast outlines a 3% year-over-year increase in global TWS unit shipments for 2025, signaling a transition from rapid growth to a more mature phase for the category. While Apple is set to remain the leading brand by...
Wi Fi WiFi General Feature

iOS 26 Adds a Useful New Wi-Fi Feature to Your iPhone

Wednesday July 2, 2025 6:36 am PDT by
iOS 26 and iPadOS 26 add a smaller yet useful Wi-Fi feature to iPhones and iPads. As spotted by Creative Strategies analyst Max Weinbach, sign-in details for captive Wi-Fi networks are now synced across iPhones and iPads running iOS 26 and iPadOS 26. For example, while Weinbach was staying at a Hilton hotel, his iPhone prompted him to fill in Wi-Fi details from his iPad that was already...
iOS 18

Apple Releases Second iOS 18.6 Public Beta

Tuesday July 1, 2025 10:19 am PDT by
Apple today seeded the second betas of upcoming iOS 18.6 and iPadOS 18.6 updates to public beta testers, with the betas coming just a day after Apple provided the betas to developers. Apple has also released a second beta of macOS Sequoia 15.6. Testers who have signed up for beta updates through Apple's beta site can download iOS 18.6 and iPadOS 18.6 from the Settings app on a compatible...

Top Rated Comments

bevel Avatar
36 months ago
Come on Apple! How long is this going to take to fix? For a company that prides itself on privacy this is not good enough
Score: 49 Votes (Like | Disagree)
DEMinSoCAL Avatar
36 months ago
Looks like the phone that prides itself on privacy isn't so private after all.
Score: 39 Votes (Like | Disagree)
icanhazmac Avatar
36 months ago

an issue that Apple has purportedly known about for years
This is the most troubling part! Apple has the resources to fix anything they want to fix, why haven't they fixed this?
Score: 34 Votes (Like | Disagree)
SW3029 Avatar
36 months ago
**** Apple. There's a damn difference between real privacy and security and real good privacy and security marketing.
Score: 34 Votes (Like | Disagree)
cjbriare Avatar
36 months ago

vpn is no privacy tool, it is for connecting 2 networks secure. Don't try to change a feature to do a thing it is not meant to do...
what does the P stand for again?
Score: 28 Votes (Like | Disagree)
nt5672 Avatar
36 months ago

Come on Apple! How long is this going to take to fix? For a company that prides itself on privacy this is not good enough
Their pride is for marketing purposes, not real life.
Score: 22 Votes (Like | Disagree)