Preface: As of March 8, 2026, Apple had released iOS 26.3.1 between March 4 and 5, 2026. Although you saw related news on March 7, this version mainly focused on bug fixes and performance optimizations for the major update released a few days earlier. The focus of this discussion is sandbox escape.
Background: iOS uses a centralized, kernel-level sandboxing system (Sandbox.kext) for all apps, primarily relying on a single default, complex profile named container.sb for all third-party applications. While the container is standard, iOS dynamically applies unique sandbox profiles to individual processes to restrict file system, hardware, and network access.
Apple states that App Groups allow multiple apps and extensions to access a shared container and perform interprocess communication.
That means:
- App ✅
- Widget ✅
- Extension ✅
…can all touch the same file path, simultaneously, in different processes.
The sandbox permits this — it does not serialize it for you.
Vulnerability details: A logic issue was addressed with improved checks. This issue is fixed in watchOS 26.3, macOS Tahoe 26.3, macOS Sonoma 14.8.4, macOS Sequoia 15.7.4, iOS 26.3 and iPadOS 26.3. An app may be able to break out of its sandbox.
Official announcement: Please refer to the link for details – https://nvd.nist.gov/vuln/detail/CVE-2026-20667