diff --git a/.cargo/config.toml.in b/.cargo/config.toml.in
index 5dfd02e06a6..5fafc0415ad 100644
--- a/.cargo/config.toml.in
+++ b/.cargo/config.toml.in
@@ -85,9 +85,9 @@ git = "https://github.com/mozilla/audioipc"
 rev = "c8d3f03cb5f889e4cab18cc1360ad0daa074f17a"
 replace-with = "vendored-sources"
 
-[source."git+https://github.com/mozilla/cubeb-coreaudio-rs?rev=ee717924ccfefc3b0b58e52968a9036b73f56f9e"]
+[source."git+https://github.com/mozilla/cubeb-coreaudio-rs?rev=5b689a7f90086e07c271ad1cf79325ee06112ab6"]
 git = "https://github.com/mozilla/cubeb-coreaudio-rs"
-rev = "ee717924ccfefc3b0b58e52968a9036b73f56f9e"
+rev = "5b689a7f90086e07c271ad1cf79325ee06112ab6"
 replace-with = "vendored-sources"
 
 [source."git+https://github.com/mozilla/cubeb-pulse-rs?rev=9cebfcceb073e9dd10cfb275a7590bca58d4c251"]
diff --git a/Cargo.lock b/Cargo.lock
index c362540f8f0..56890117947 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1090,7 +1090,7 @@ dependencies = [
 [[package]]
 name = "coreaudio-sys-utils"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/cubeb-coreaudio-rs?rev=ee717924ccfefc3b0b58e52968a9036b73f56f9e#ee717924ccfefc3b0b58e52968a9036b73f56f9e"
+source = "git+https://github.com/mozilla/cubeb-coreaudio-rs?rev=5b689a7f90086e07c271ad1cf79325ee06112ab6#5b689a7f90086e07c271ad1cf79325ee06112ab6"
 dependencies = [
  "core-foundation-sys",
  "coreaudio-sys",
@@ -1436,7 +1436,7 @@ dependencies = [
 [[package]]
 name = "cubeb-coreaudio"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/cubeb-coreaudio-rs?rev=ee717924ccfefc3b0b58e52968a9036b73f56f9e#ee717924ccfefc3b0b58e52968a9036b73f56f9e"
+source = "git+https://github.com/mozilla/cubeb-coreaudio-rs?rev=5b689a7f90086e07c271ad1cf79325ee06112ab6#5b689a7f90086e07c271ad1cf79325ee06112ab6"
 dependencies = [
  "atomic",
  "audio-mixer",
diff --git a/third_party/rust/coremidi/.cargo-checksum.json b/third_party/rust/coremidi/.cargo-checksum.json
index a4ed7d3b066..b83a7900846 100644
--- a/third_party/rust/coremidi/.cargo-checksum.json
+++ b/third_party/rust/coremidi/.cargo-checksum.json
@@ -1 +1 @@
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\ No newline at end of file
+{"files":{".cargo_vcs_info.json":"027854b9a546ff3bcce94fe10ad83debd7570429aadd23e360dde32935aea52a",".github/workflows/deploy.yaml":"de84428eb35f3b6617704d80dbb916987d9a4fbaf1d2a5b1a52a1c4c60d89c94",".github/workflows/test.yaml":"7a8e59be2e1a4253dd277874257003a20a1149de891749f701910a270c69a3af","Cargo.lock":"5e5dd0b8006fbcc96bff6908978ddce772095a95a8b8e8bd29601b862991bef2","Cargo.toml":"505c6ef2f5e1dda024ea65c0ea8f5d3bb05f3b017d2c9e4463a25c838ea208e2","Cargo.toml.orig":"70de399a10af67ae1d1d8660c6ddec5b10ceefc23b3d84767362d06f9416f7d2","LICENSE":"c1c457e1b2794c9044f0e2d66a7010c223d0fb65b06e1dfbab6e21888ab09c16","README.md":"e55bfa1cadbbf497d28f3c9fc470eb381ff3c9ef7bbc3bcb7828a097924e21ab","examples/endpoints.rs":"4431c57aaf70ee9bec3bc3eb97ccc0d92673cdb49f67c8d81e9caf1fb1a5a213","examples/notifications.rs":"8aed2404777a2d68efc4ddb89ad8f612b20045e1bc1a67df943b8f31ba32e322","examples/properties.rs":"37c0c205f7677ff18caa1258a3c88313ce06033facc025adf7364db5bddeb5df","examples/receive.rs":"4a754506f9f89e58d4abcc5148f39a501e79f4ca7768e31ff8ac808deb59d2f9","examples/send.rs":"35b4ea48c405e085e918c91831d9ac9a89312da66540cdb0e4e6e22647565503","examples/virtual-destination.rs":"2c44bd1a704d3c6ea3a379921f7a91bcd0c51f6e85787c5fa816c5983d07e76e","examples/virtual-source.rs":"e9444b89a940911e946e98ab23979407b724b4487501cd7f2bc74507eed8deec","rust-toolchain":"b104646411661bf06fc72347bbb9966cded636b50c02f722d7e8b8f2131a5aff","src/any_object.rs":"2f3586da54ad8252e452c51c0342b2721db3094e33bcfae5f590049808959234","src/client.rs":"0a41d7cf4286fef3dd22348079aac27beee2c32fdb9f72c31254645f781571f9","src/device.rs":"a9c470f28c14b45ecfca9d96a275388238b74bbea3594f28a8741ce6fa975690","src/endpoints/destinations.rs":"77f2df648df7c69afbca33206539c7131e0d7192f03c0fa9ef9947f63cda9a1c","src/endpoints/endpoint.rs":"84715d6f175cbc2fcdb4cbcd8ab9db9c745fc50b1b1853919078fa20c16fe1a3","src/endpoints/mod.rs":"5750836ea1bbc4914e41fa29ffe1ecb5c289933a94875777a00272acb9fd5b11","src/endpoints/sources.rs":"a71c79e32d2a0647df6f4d5da5ba7d71bd55948cf4436df1b6089a30cd7ea692","src/entity.rs":"5b02ffd6207842e84a8c5c73d7439c6d39881aac04a0099258d0e16a21668ecb","src/events.rs":"40b4c7d5b2e7afa6b5213aad6114cc92c2122acb08d77fbf15bd0ba48207e53e","src/lib.rs":"ed0e9016b9d9ffb9b638ed63738c3f0623e17900a19fe16f009d77fd5d20a81e","src/notifications.rs":"0ab5c2f169c7b4515b294aa960bf83327c109a62e343019602517cf726712b7c","src/object.rs":"c5b4162898b1a295bcdcd4ab2042752adfd1aef1a4dd8c048407ffe60cdf4630","src/packets.rs":"8d1dd5c274567077ed7dbed614b103f1519b2b58ca251d3627828d9eab8850ad","src/ports.rs":"cf0c3e168e42e5b8e32ac86044453ca36cb17adb54dbfc36470f751f4d36dccc","src/properties.rs":"4b3bd650be9ca163b34868fc98e282bf4e9ed216500ff0513b169c03a7a7ec97","src/protocol.rs":"811f87c29e67adad51980930b692a413bfdb4f41130de8a3f8e8fce99159a3a3"},"package":"964eb3e10ea8b0d29c797086aab3ca730f75e06dced0cb980642fd274a5cca30"}
\ No newline at end of file
diff --git a/third_party/rust/coremidi/.idea/.gitignore b/third_party/rust/coremidi/.idea/.gitignore
deleted file mode 100644
index 62c893550ad..00000000000
--- a/third_party/rust/coremidi/.idea/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-.idea/
\ No newline at end of file
diff --git a/third_party/rust/cubeb-coreaudio/.cargo-checksum.json b/third_party/rust/cubeb-coreaudio/.cargo-checksum.json
index 6d6de08d46a..2c370b77df0 100644
--- a/third_party/rust/cubeb-coreaudio/.cargo-checksum.json
+++ b/third_party/rust/cubeb-coreaudio/.cargo-checksum.json
@@ -1 +1 @@
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\ No newline at end of file
diff --git a/third_party/rust/cubeb-coreaudio/src/backend/aggregate_device.rs b/third_party/rust/cubeb-coreaudio/src/backend/aggregate_device.rs
index 27c07e33b7e..e4558ec380f 100644
--- a/third_party/rust/cubeb-coreaudio/src/backend/aggregate_device.rs
+++ b/third_party/rust/cubeb-coreaudio/src/backend/aggregate_device.rs
@@ -152,9 +152,9 @@ impl AggregateDevice {
         debug_assert_running_serially();
         let waiting_time = Duration::new(5, 0);
 
-        let condvar_pair = Arc::new((Mutex::new(()), Condvar::new()));
-        let mut cloned_condvar_pair = condvar_pair.clone();
-        let data_ptr = &mut cloned_condvar_pair as *mut Arc<(Mutex<()>, Condvar)>;
+        let condvar_pair = Box::new((Mutex::new(()), Condvar::new()));
+        let data_ptr = Box::into_raw(condvar_pair);
+        sync_callback_registry_register(data_ptr as usize);
 
         let address = get_property_address(
             Property::HardwareDevices,
@@ -177,12 +177,14 @@ impl AggregateDevice {
                 data_ptr as *mut c_void,
             );
             assert_eq!(status, NO_ERR);
+            sync_callback_registry_unregister(data_ptr as usize);
+            unsafe { drop(Box::from_raw(data_ptr)) };
         });
 
         let device = Self::create_blank_device(plugin_id)?;
 
         // Wait until the aggregate is created.
-        let (lock, cvar) = &*condvar_pair;
+        let (lock, cvar) = unsafe { &*data_ptr };
         let guard = lock.lock().unwrap();
         let (_guard, timeout_res) = cvar
             .wait_timeout_while(guard, waiting_time, |()| !get_devices().contains(&device))
@@ -202,10 +204,12 @@ impl AggregateDevice {
             data: *mut c_void,
         ) -> OSStatus {
             assert_eq!(id, kAudioObjectSystemObject);
-            let pair = unsafe { &mut *(data as *mut Arc<(Mutex<()>, Condvar)>) };
-            let (lock, cvar) = &**pair;
-            let _guard = lock.lock().unwrap();
-            cvar.notify_one();
+            with_sync_callback_ptr(data, || {
+                let pair = unsafe { &*(data as *const (Mutex<()>, Condvar)) };
+                let (lock, cvar) = pair;
+                let _guard = lock.lock().unwrap();
+                cvar.notify_one();
+            });
             NO_ERR
         }
 
@@ -314,9 +318,9 @@ impl AggregateDevice {
 
         let waiting_time = Duration::new(5, 0);
 
-        let condvar_pair = Arc::new((Mutex::new(AudioObjectID::default()), Condvar::new()));
-        let mut cloned_condvar_pair = condvar_pair.clone();
-        let data_ptr = &mut cloned_condvar_pair as *mut Arc<(Mutex<AudioObjectID>, Condvar)>;
+        let condvar_pair = Box::new((Mutex::new(AudioObjectID::default()), Condvar::new()));
+        let data_ptr = Box::into_raw(condvar_pair);
+        sync_callback_registry_register(data_ptr as usize);
 
         let status = audio_object_add_property_listener(
             device_id,
@@ -325,22 +329,27 @@ impl AggregateDevice {
             data_ptr as *mut c_void,
         );
         if status != NO_ERR {
+            sync_callback_registry_unregister(data_ptr as usize);
+            unsafe { drop(Box::from_raw(data_ptr)) };
             return Err(Error::from(status));
         }
 
-        let remove_listener = || -> OSStatus {
-            audio_object_remove_property_listener(
+        let cleanup = || {
+            let status = audio_object_remove_property_listener(
                 device_id,
                 &address,
                 devices_changed_callback,
                 data_ptr as *mut c_void,
-            )
+            );
+            sync_callback_registry_unregister(data_ptr as usize);
+            unsafe { drop(Box::from_raw(data_ptr)) };
+            status
         };
 
         Self::set_sub_devices(device_id, input_id, output_id)?;
 
         // Wait until the sub devices are added.
-        let (lock, cvar) = &*condvar_pair;
+        let (lock, cvar) = unsafe { &*data_ptr };
         let device = lock.lock().unwrap();
         if *device != device_id {
             let (dev, timeout_res) = cvar.wait_timeout(device, waiting_time).unwrap();
@@ -353,13 +362,10 @@ impl AggregateDevice {
                 );
             }
             if *dev != device_id {
-                let status = remove_listener();
+                let status = cleanup();
                 // If the error is kAudioHardwareBadObjectError, it implies `device_id` is somehow
                 // dead, so its listener should receive nothing. It's ok to leave here.
                 assert!(status == NO_ERR || status == (kAudioHardwareBadObjectError as OSStatus));
-                // TODO: Destroy the aggregate device immediately if error is not
-                // kAudioHardwareBadObjectError. Otherwise the `devices_changed_callback` is able
-                // to touch the `cloned_condvar_pair` after it's freed.
                 return Err(Error::from(waiting_time));
             }
         }
@@ -370,15 +376,17 @@ impl AggregateDevice {
             _addresses: *const AudioObjectPropertyAddress,
             data: *mut c_void,
         ) -> OSStatus {
-            let pair = unsafe { &mut *(data as *mut Arc<(Mutex<AudioObjectID>, Condvar)>) };
-            let (lock, cvar) = &**pair;
-            let mut device = lock.lock().unwrap();
-            *device = id;
-            cvar.notify_one();
+            with_sync_callback_ptr(data, || {
+                let pair = unsafe { &*(data as *const (Mutex<AudioObjectID>, Condvar)) };
+                let (lock, cvar) = pair;
+                let mut device = lock.lock().unwrap();
+                *device = id;
+                cvar.notify_one();
+            });
             NO_ERR
         }
 
-        let status = remove_listener();
+        let status = cleanup();
         assert_eq!(status, NO_ERR);
         Ok(())
     }
diff --git a/third_party/rust/cubeb-coreaudio/src/backend/mod.rs b/third_party/rust/cubeb-coreaudio/src/backend/mod.rs
index 210a9f33e12..023a7210b65 100644

diff --git a/third_party/rust/cubeb-coreaudio/src/backend/tests/mod.rs b/third_party/rust/cubeb-coreaudio/src/backend/tests/mod.rs
index 0c193d0dc8f..9406c9ecfa7 100644
--- a/third_party/rust/cubeb-coreaudio/src/backend/tests/mod.rs
+++ b/third_party/rust/cubeb-coreaudio/src/backend/tests/mod.rs
@@ -8,5 +8,6 @@ mod device_property;
 mod interfaces;
 mod manual;
 mod parallel;
+mod sync_callback;
 mod tone;
 mod utils;
diff --git a/third_party/rust/cubeb-coreaudio/src/backend/tests/sync_callback.rs b/third_party/rust/cubeb-coreaudio/src/backend/tests/sync_callback.rs
new file mode 100644
index 00000000000..6930dc7ecce
--- /dev/null
+++ b/third_party/rust/cubeb-coreaudio/src/backend/tests/sync_callback.rs
@@ -0,0 +1,136 @@
+// Copyright © 2026 Mozilla Foundation
+//
+// This program is made available under an ISC-style license.  See the
+// accompanying file LICENSE for details.
+
+use super::*;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Arc;
+
+// Test basic registration and unregistration
+#[test]
+fn test_sync_callback_register_unregister() {
+    let dummy_data = Box::new(42u32);
+    let ptr = Box::into_raw(dummy_data);
+    let ptr_usize = ptr as usize;
+
+    // Register the pointer
+    sync_callback_registry_register(ptr_usize);
+
+    // Verify the callback is called when registered
+    let called = Arc::new(AtomicBool::new(false));
+    let called_clone = called.clone();
+    with_sync_callback_ptr(ptr as *mut c_void, || {
+        called_clone.store(true, Ordering::SeqCst);
+    });
+    assert!(
+        called.load(Ordering::SeqCst),
+        "Callback should be called when pointer is registered"
+    );
+
+    // Unregister the pointer
+    sync_callback_registry_unregister(ptr_usize);
+
+    // Verify the callback is NOT called after unregistration
+    let called2 = Arc::new(AtomicBool::new(false));
+    let called2_clone = called2.clone();
+    with_sync_callback_ptr(ptr as *mut c_void, || {
+        called2_clone.store(true, Ordering::SeqCst);
+    });
+    assert!(
+        !called2.load(Ordering::SeqCst),
+        "Callback should NOT be called after unregistration"
+    );
+
+    // Clean up
+    unsafe { drop(Box::from_raw(ptr)) };
+}
+
+// Test that unregistered pointers don't trigger callbacks
+#[test]
+fn test_sync_callback_unregistered_pointer() {
+    let dummy_data = Box::new(100u32);
+    let ptr = Box::into_raw(dummy_data);
+
+    // Try to use callback without registration
+    let called = Arc::new(AtomicBool::new(false));
+    let called_clone = called.clone();
+    with_sync_callback_ptr(ptr as *mut c_void, || {
+        called_clone.store(true, Ordering::SeqCst);
+    });
+    assert!(
+        !called.load(Ordering::SeqCst),
+        "Callback should NOT be called for unregistered pointer"
+    );
+
+    // Clean up
+    unsafe { drop(Box::from_raw(ptr)) };
+}
+
+// Test multiple registrations don't cause issues
+#[test]
+fn test_sync_callback_multiple_pointers() {
+    let data1 = Box::new(1u32);
+    let ptr1 = Box::into_raw(data1);
+    let ptr1_usize = ptr1 as usize;
+
+    let data2 = Box::new(2u32);
+    let ptr2 = Box::into_raw(data2);
+    let ptr2_usize = ptr2 as usize;
+
+    // Register both pointers
+    sync_callback_registry_register(ptr1_usize);
+    sync_callback_registry_register(ptr2_usize);
+
+    // Both should work
+    let called1 = Arc::new(AtomicBool::new(false));
+    let called1_clone = called1.clone();
+    with_sync_callback_ptr(ptr1 as *mut c_void, || {
+        called1_clone.store(true, Ordering::SeqCst);
+    });
+    assert!(
+        called1.load(Ordering::SeqCst),
+        "First pointer callback should be called"
+    );
+
+    let called2 = Arc::new(AtomicBool::new(false));
+    let called2_clone = called2.clone();
+    with_sync_callback_ptr(ptr2 as *mut c_void, || {
+        called2_clone.store(true, Ordering::SeqCst);
+    });
+    assert!(
+        called2.load(Ordering::SeqCst),
+        "Second pointer callback should be called"
+    );
+
+    // Unregister first pointer
+    sync_callback_registry_unregister(ptr1_usize);
+
+    // First should not work, second should still work
+    let called1_after = Arc::new(AtomicBool::new(false));
+    let called1_after_clone = called1_after.clone();
+    with_sync_callback_ptr(ptr1 as *mut c_void, || {
+        called1_after_clone.store(true, Ordering::SeqCst);
+    });
+    assert!(
+        !called1_after.load(Ordering::SeqCst),
+        "First pointer callback should NOT be called after unregister"
+    );
+
+    let called2_after = Arc::new(AtomicBool::new(false));
+    let called2_after_clone = called2_after.clone();
+    with_sync_callback_ptr(ptr2 as *mut c_void, || {
+        called2_after_clone.store(true, Ordering::SeqCst);
+    });
+    assert!(
+        called2_after.load(Ordering::SeqCst),
+        "Second pointer callback should still be called"
+    );
+
+    // Clean up
+    sync_callback_registry_unregister(ptr2_usize);
+    unsafe {
+        drop(Box::from_raw(ptr1));
+        drop(Box::from_raw(ptr2));
+    };
+}
diff --git a/third_party/rust/unicode-ident/tests/fst/.gitignore b/third_party/rust/unicode-ident/tests/fst/.gitignore
deleted file mode 100644
index 0d101a4a953..00000000000
--- a/third_party/rust/unicode-ident/tests/fst/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-prop_list.rs
diff --git a/third_party/rust/wast/tests/.gitattributes b/third_party/rust/wast/tests/.gitattributes
deleted file mode 100644
index 75de48a520a..00000000000
--- a/third_party/rust/wast/tests/.gitattributes
+++ /dev/null
@@ -1 +0,0 @@
-parse-fail/newline-in-string.wat text eol=lf
diff --git a/third_party/rust/wast/tests/.gitignore b/third_party/rust/wast/tests/.gitignore
deleted file mode 100644
index 265315a8623..00000000000
--- a/third_party/rust/wast/tests/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-!*.wat