A significant vulnerability in Apple's Private Relay feature undermines one of the company's flagship privacy protections, allowing user IP addresses to leak onto the internet despite subscribers paying for the premium security service. The flaw, discovered by cybersecurity researchers Talal Haj Bakry and Tommy Mysk, affects not only Apple's own iCloud+ Private Relay subscribers but also alternative browsers on iOS that depend on Apple's required WebKit engine, including privacy-focused applications like the Tor browser and Psylo, a private browser developed by the researchers themselves.
The researchers identified three separate defects within WebKit, the browser engine that Apple mandates all iOS browsers must use under App Store policy. These flaws create conditions for DNS leaks—a type of data exposure where the addresses of websites users visit can be revealed—and directly expose the real IP address of a device. The vulnerability was flagged on August 5 in a detailed technical post that highlighted how the problem persists even when users have activated Private Relay, which Apple positions as its most robust protection against tracking and location inference.
The discovery emerged when a user of Psylo reported experiencing DNS leaks on certain websites. Upon investigation, the researchers traced the issue to the mandatory WebKit dependency and uncovered two additional related vulnerabilities that similarly compromise device IP address confidentiality. The implications extend across the entire iOS ecosystem because Apple's regulatory framework leaves developers no choice but to implement Apple's browser technology, regardless of whether they are building alternative privacy tools.
Particularly troubling is that one of the pathways for IP exposure stems ironically from another security mechanism. When users employ passkeys—a newer, more secure authentication method designed to replace traditional passwords—their devices must make requests that fall outside the normal browser process. This architectural necessity causes passkey traffic to bypass Private Relay's protective relay system entirely, creating an unintended opening through which genuine IP addresses escape. For users who believe they are protected by Private Relay while using passkeys, the service provides no protection whatsoever.
Private Relay, which Apple introduced in 2021 as a premium iCloud+ feature, operates through a dual-relay architecture intended to ensure that no single entity, including Apple itself, can simultaneously view both a user's identity and their browsing behaviour. The system was presented as the evolution of Apple's earlier Intelligent Tracking Prevention and represented a significant step beyond conventional privacy browsing modes. By inserting two intermediary servers into the connection process, Private Relay theoretically shields users from internet service providers, website operators, and advertisers who might otherwise track their online movements and approximate location.
IP addresses function as digital identifiers for all internet-connected devices, revealing considerable personal information in the process. These numerical addresses pinpoint a user's approximate geographic location to the postal code level, enabling service providers and website administrators to construct detailed profiles of browsing habits and online behaviour. Beyond privacy concerns, exposed IP addresses provide malicious actors with vectors for launching specific categories of cyberattacks, from distributed denial-of-service assaults to targeted intrusions. The concealment of IP addresses has therefore become a standard expectation among users prioritising online security and anonymity.
Apple has consistently marketed its products and services as privacy-centric, building brand identity around the premise that user data protection is embedded throughout its ecosystem. The company invested in advertising campaigns, including a prominent June initiative promoting Safari's privacy advantages over competitors such as Google Chrome. This narrative of privacy-first design extends back to 2017, when Apple deployed Intelligent Tracking Prevention to restrict trackers' ability to monitor users. Private Relay represented the logical extension of this positioning, offering premium subscribers what Apple described as enterprise-grade protection against location inference and activity tracking.
The distinction between Private Relay and Safari's separate Private Browsing mode is important for users to understand. Private Browsing provides modest protections such as preventing local history storage and clearing cookies within private tabs, but it offers no IP address masking or protection against network-level tracking. Private Relay, by contrast, is specifically designed to mask network-level identifiers and should function across all applications on a device. The vulnerability discovered by the researchers demonstrates that this comprehensive protection fails in realistic usage scenarios when users authenticate through passkeys, a feature Apple itself has promoted as a modern security improvement.
Responses from the affected developer community indicate active mitigation efforts. The researchers updated Psylo to defend against the identified flaws and notified developers of the Tor Project and Onion Browser so they could implement similar protections. However, these patches address only the symptoms rather than the underlying architectural problem: iOS developers cannot modify or replace WebKit, meaning the core vulnerability persists within Apple's mandatory browser engine. Users of Safari and other iOS browsers remain exposed until Apple itself releases security patches that fundamentally restructure how passkey authentication integrates with Private Relay.
The timing and scope of this vulnerability raises questions about Apple's testing and quality assurance processes for privacy-critical features. A flaw affecting the mechanism through which Private Relay handles authentication—a fundamental interaction—suggests insufficient scrutiny of real-world usage patterns before deployment. For Malaysian and Southeast Asian users, who increasingly depend on privacy tools to navigate regional internet environments with varying data protection standards, the discovery underscores that brand reputation for privacy alone provides insufficient assurance. Technical verification and independent security audits remain essential safeguards.
