Crash in BraintreeCore/BTWebAuthenticationSession.swift starting in v6.35.0

[ecant]

Braintree SDK Version

6.35.0 and above

Environment

Production

Xcode Version

Xcode 16.4.0

OS Version & Device

Seems to span multiple iOS versions and devices (including most recent iOS 18.6.2 and iPhone 16 Pro)

Integration type

Swfit Package Manager

Development Processor

Apple Silicon (M-series chips)

Describe the bug

Summary

Our crash reporting system started reporting app crashes in the first version where we upgraded the Braintree iOS SDK from 6.34.0 to 6.35.0. We're on 6.37.0 now and the issue is still occurring.

We haven't made any code changes in our payments code that integrates with the Braintree SDK for months, so long before when this started happening.

The crash does not consistently happen, and it occurs at various points in the user journey, so there appears to be a race or timing issue of some sort involved. However, it has affected over a thousand clients in the past month.

Crash info

The crash report is consistent however: a segmentation fault when calling BTWebAuthenticationSession.start(...). The crash consistently reports as occurring on line 43 of BTWebAuthenticationSession.swift, inside the main-queue closure that invokes sessionDidAppear(self.currentSession?.start() ?? false).

FWIW, I can see there were some code changes in BTWebAuthenticationSession.swift starting in SDK version 6.35.0, which is the version we started experiencing this crash.

Here is an example screenshot of the crash stack trace:

To reproduce

I have tried to reproduce this on my local device but can't so far. However, like I mentioned, we have crash reports from a thousand+ users.

Expected behavior

The SDK doesn't cause a crash in our app.

Screenshots

No response

[richherrera]

Thanks for reporting this issue and sharing the details.
I’ll review it with the team and provide an update as soon as I have more information.

[richherrera]

In the meantime, could you also share a code snippet of your integration? That would help us better understand how BTWebAuthenticationSession is being triggered in your case.

Additionally, could you let us know which integration you are using (e.g., PayPal, LocalPayment, SEPADirect, etc.)? This context will help us narrow down the investigation.

[ecant]

Additionally, could you let us know which integration you are using (e.g., PayPal, LocalPayment, SEPADirect, etc.)? This context will help us narrow down the investigation.

We accept Credit Card, PayPal, ApplePay, and Venmo payments via Braintree in our app. This is the unique list of the package products we import in our app.

import BraintreeCore
import BraintreeCard
import BraintreeApplePay
import BraintreePayPal
import BraintreeThreeDSecure
import BraintreeVenmo

In the meantime, could you also share a code snippet of your integration? That would help us better understand how BTWebAuthenticationSession is being triggered in your case.

I should probably clarify that we are not calling BTWebAuthenticationSession directly (I know that is an internal use class) - that's just where the crash is happening.

From looking at where BTWebAuthenticationSession is used in the Braintree codebase, I think the only thing we're directly using that references it is the BTPayPalClient.

This is the call site for that in our codebase:

extension BTAPIClient {
    func requestPayPalBillingAgreement(request: BTPayPalVaultRequest,
                                       completion: @escaping (BraintreePayPalAccountNonce?, BraintreeError?) -> Void) {
        let payPalDriver = BTPayPalClient(apiClient: self)
        payPalDriver.tokenize(request) { nonce, error in
            var wrappedError: BraintreeError?
            if let error = error {
                wrappedError = BraintreeError(error: error)
            }
            completion(nonce, wrappedError)
        }
    }
}

Let me know if you need any other info! Thank you!