Xcode 26.x + iOS 26.x MTE Compatibility Feedback

Question

Created 1d

Replies 2

Boosts 0

Participants 2

Xcode 26.x + iOS 26.x MTE Compatibility Feedback

Reporter：Third-party App Developer Date：2026 Environments：Xcode 26.2 / 26.4, iOS 26.2 / 26.4 SDK, iPhone 17 Pro, Third-party App (Swift/C++/Python/Boost)

Core Issue

MTE (Memory Tagging Extension) under Memory Integrity Enforcement generates extensive false positives for valid high-performance memory operations in third-party apps, causing crashes. No official configuration exists to bypass these false positives, severely impacting stability and development costs.

Key Problems

1. Widespread False Positives (Valid Code Crashes)

After enabling MTE (Soft/Hard Mode), legitimate industrial-standard operations crash:

Swift/ C++ containers: Array.append, resize, std::vector reallocation
Custom memory pools / Boost lockfree queues:no UAF/corruption
Memory reallocation:Legitimate free-reuse patterns are judged as tag mismatches.

2. MTE Hard Mode Incompatibility

iOS 26.4 opens MTE Hard Mode for third-party apps, but it immediately crashes apps using standard high-performance memory management.
No whitelist/exception mechanism for third-party developers.

3. MTE Soft Mode Limitations

Detects far fewer issues than actual memory corruption reports.
Only generates 1 simulated report per process, hiding multiple potential issues.

Impact

Stability: Apps crash in production when MTE is enabled.
Cost: Massive code changes required to abandon memory pools/lockfree structures for system malloc.
Ecosystem: Popular libraries (Python, Boost) are incompatible.

Recommendations

Optimize MTE rules: Add system-level exceptions for valid container resizing and memory pool operations.
Provide exemptions: Allow per-region/module MTE exceptions for high-performance modules.
Support runtimes: Officially support common third-party runtimes (Python/Boost) or provide system-level exemptions.
Improve debugging: Increase MTE Soft Mode coverage and allow multiple reports per process.

Answered by DTS Engineer in 883471022

The best way to get this feedback to the right people is by filing it officially in Feedback Assistant. See Bug Reporting: How and Why? for lots of hints and tips on the process.

I recommend that you split this up into multiple reports. You have a lot of different suggestions and things usually work out better when you split them up [1].

Please post your bug number — well, bug numbers — just for the record.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

[1] We can split things up internally, but then you lose the ability to get any sort of status information, because those internal bug reports are no long associated with your team.

Boost

Answer 1

DTS Engineer OP

Apple

1d

Recommended

The best way to get this feedback to the right people is by filing it officially in Feedback Assistant. See Bug Reporting: How and Why? for lots of hints and tips on the process.

I recommend that you split this up into multiple reports. You have a lot of different suggestions and things usually work out better when you split them up [1].

Please post your bug number — well, bug numbers — just for the record.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

[1] We can split things up internally, but then you lose the ability to get any sort of status information, because those internal bug reports are no long associated with your team.

0

Answer 2

monkey_1 OP

1d

Thank you very much for your valuable guidance on our MTE (Memory Integrity Enforcement) compatibility feedback for Xcode 26.x and iOS 26.x. We will follow your recommendation to split the feedback into multiple reports and file them officially in Feedback Assistant. We will share the bug numbers with you for the record once the reports are filed.

0