EFF Report: Ad Libraries Covertly Leak Location Data from Apps

As reported by Hudson Hongo on EFF Deeplinks, the Electronic Frontier Foundation (EFF) has released new research findings on privacy violations by mobile ad libraries. The report details the mechanisms by which ad software transmits users’ location data externally, often without the app developers themselves being aware of it.

Background and Overview of the Investigation

The EFF’s investigation focused on ad libraries embedded in numerous apps, commonly known as ad SDKs (Software Development Kits). These kits demand extensive permissions for ad delivery and analytics, which can include access to location information. The advertising industry views location data as an “asset with significant market value,” a sector now worth billions of dollars.

The core of the report is that ad libraries transcend the scope of data collection, acting without the developer’s intent or consent. In cases analyzed by the EFF, multiple ad SDKs were found to be fetching and transmitting location data. This process is likely not clearly visible in the developer’s code or is obscured within the scope of permission requests.

Data Collection Unnoticed by Developers

According to the EFF’s report, the root of the problem lies in the opacity of ad library operations. Developers typically anticipate ad delivery and basic analytics when integrating an ad SDK into their apps. However, the actual behavior of these libraries can deviate from this expectation.

Specifically, the ad library requests access to location data through the OS (operating system) permission framework, and once approved, it sends that data to its own servers. This entire sequence of actions is carried out by the library’s internal logic, even without the developer explicitly instructing location data collection. As a result, cases occur where developers remain unaware that their own app is compromising user privacy.

Structural Problems in the Ad Ecosystem

This issue is not merely a technical vulnerability but is rooted in the structure of the advertising technology ecosystem. Advertisers demand location data strongly for more precise targeting, and ad platforms collect detailed information to meet this demand. This pressure is believed to motivate ad library developers and operators to engage in more aggressive data collection.

The EFF’s investigation suggests that much of this data collection is conducted under the guise of legitimate purposes like “ad effectiveness measurement” or “fraud prevention.” However, the scope and precision of the collected information clearly exceed what is necessary for measuring ad effectiveness. Consequently, highly sensitive information, such as users’ daily movement patterns and visited locations, is being collected for commercial purposes.

Responsibility of Developers and Platforms

The EFF’s report also serves as a warning to app developers. Developers are being pressed to more strictly monitor the behavior of the third-party components they integrate. In the current development environment, it is not easy to fully understand and monitor the internal workings of ad SDKs. This is not an issue of the developers’ technical capability but a structural challenge caused by the opacity of the advertising ecosystem.

On the other hand, platform operators like Google and Apple also bear responsibility. They manage apps through the App Store and Google Play and enforce privacy policies. However, the current review process is not sufficiently detecting the problem of ad libraries collecting data beyond the developer’s intent. The EFF points this out and calls for more proactive intervention and increased transparency from platforms.

Future Outlook and EFF’s Proposals

Through this report, the EFF is demanding increased transparency across the entire ad technology industry and effective information disclosure to users. Specifically, it proposes establishing a mechanism that clearly notifies not just developers, but also end-users, about what data is collected and transmitted by ad libraries.

Furthermore, the EFF urges developers to prioritize privacy considerations when selecting ad SDKs to integrate into their apps. It also calls on platform operators to strengthen their policies by scrutinizing ad SDK operations more rigorously and excluding those suspected of privacy violations.

Related Articles

This case is part of a broader discussion on digital privacy and advertising technology. The following past reports may also be of reference:

• Mesa 26.2-rc1 Released, with Vulkan Extensions and Rusticl OpenCL 3.1 Support — The evolution of open-source graphics stacks could also impact on-device data processing and privacy.
• Ctrl-F Plus for Chrome: “Search All Tabs” Changes the Ctrl+F Paradigm — Expansions in browser functionality need to be reconsidered in the context of expanding the scope of user behavior data collection.
• Meta Pauses Subscription for “Conversation Focus” — Meta’s collection of visual information through smart glasses, when combined with location data, poses further privacy risks.

Editorial Opinion

This EFF report once again makes visible the privacy risks posed by the “hidden code working behind the scenes” of advertising technology. In the short term, it will likely create pressure on the developer community and platform operators to audit third-party libraries and improve transparency. It cannot be ruled out that the review processes of the App Store and Google Play may incorporate analysis of ad SDK operations. In the long term, this issue has starkly highlighted the structural tension between data collection and privacy. The high-precision targeting sought by advertisers and users’ privacy rights are fundamentally contradictory. The EFF’s investigation shows that the current ad ecosystem has not adequately resolved this contradiction, and that data collection without a technical basis has become normalized. The fundamental question that remains is whether the advertising industry possesses the will and capability to reform itself, or whether the status quo cannot be improved without external legal or technical pressure. The EFF’s proposals are important, but for many app developers dependent on ad revenue, transitioning to privacy-conscious SDKs is not an easy choice.

References

• ”📍 The Sneaky Code Tracking App Users | EFFector 38.15”, by Hudson Hongo — EFF Deeplinks, 2026-08-19T16:35:30.000Z (CC BY)
• Source URL: https://www.eff.org/deeplinks/2026/08/sneaky-code-tracking-app-users-effector-3815