WQ Files browses other apps' folders and clears their caches on iOS 26 and 27 using the worse_query sandbox trick, no jailbreak

Apple’s Files app shows you iCloud and a few folders. Settings shows a storage bar and a list of apps with a number next to each. Neither will let you open another app’s data folder, and neither has a button for “clear this app’s cache.”

WQ Files does, and doesn’t ask you to jailbreak. The README says it is built on worse_query, a sandbox technique by Taj C (forcequit), and states flatly: “This app reimplements it.” The container-listing code comes from KAMUI by murk-sus, also credited. By its description it is one sandbox technique, not a whole new exploit chain, which is also the reason to expect Apple to close it. A trick that rides a flaw is good until the flaw gets a patch.

The tested list is specific. The README says “Tested on iOS 26.7.1, 27.0.1, 27.2.1 and the 27.3 beta (confirmed by a user).” The repo has 842 stars, 61 forks and 291 commits. It installs the sideload way: add the source.json to AltStore, SideStore, LiveContainer or AltDirect, or download WQFiles.ipa and sign it yourself. Signing needs an App Group, and the README warns that “Sideloadly doesn’t add the App Group,” which makes the app report “No App Group.”

What it does is the useful part. The Apps tab backs up, restores, clears or shares an app’s Documents and Library as a ZIP. The Cache Cleaner shows cache and temp sizes per app, with Select All, None and “Large Caches (50 MB+).” The Files tab browses, edits, moves, compresses and extracts, with plist, hex and SQLite editors and a media player. Overwritten or deleted files are copied to Backups first, and a Recently Deleted list brings them back. (A trash can for other people’s apps.)

iOS 26 gets less. System Data and system groups are hidden there, and the Cache Cleaner has no crash-log section. Icons show as placeholder symbols. A full scan “would take most of an hour on iOS 26,” so the app reads the LaunchServices database instead. On 27.0.1, system group parents can’t be listed, so it tries known names one by one.

The README is blunt about breakage: “Editing another app’s or the system’s files can break things.” Close the target app before you back up, restore or clear. Clearing app data and cleaning caches delete files with no file-by-file backup. SQLite saves need the target app force-quit first. File locks are advisory, and in-place writes are not crash-atomic.

The only network traffic is an optional update check of the public source.json, at most twice a day. Turn it off and the app is fully offline. The code is GPL-3.0-or-later, so anyone can read what it does before putting it on a phone that holds their banking app.

Where this goes is a cat-and-mouse game. The pattern has been the same for years: someone finds a way into the sandbox, a tidy tool wraps it, Apple closes the hole, and the next iOS has a new quirk. Sideloading makes it easier now to keep up, because AltStore and its siblings can ship updates quickly, so the interesting question for WQ Files is how fast it can adapt rather than whether it will break.

For the rest of us, a normal-looking cache cleaner on a phone with a hidden sandbox is a good reason to read the license before the install button. GPL code you can read is the one point in its favor.

The README says real-device validation is still needed for token issuance, timing, concurrent writes and power-loss behavior. Power loss is still on the to-test list.