CVE-2026-64788 — IOGPUFamily Use-After-Free

Component: IOGPUFamily kernel extension (com.apple.iokit.IOGPUFamily)
Affected: iOS / iPadOS 26.6 (23G71) and earlier
Fixed in: iOS / iPadOS 26.6.1 (23G83)
Type: Use-After-Free in IOGPUDevice::create_resource_iosurface
Impact: Kernel memory corruption; UAF dereference confirmed on A14 (iPhone 12)

Credits

Discovered by: f00l (@PPPF00L), 3ndy1 (@_3ndy1), Minghao Lin (@Y1nkoc), 云散花折, Arjanit Isufi
(per Apple Security Advisory — iOS 26.6.1)

Root Cause

IOGPUDevice::create_resource_iosurface allocates an IOGPUSysMemory object (~0x100 bytes, kalloc.256 zone) and registers it in the device's IOSurface resource table. Before returning, a dimension overflow check fires via ADDS width+height → b.hs. The overflow path branches to an error return without releasing the object, leaving a live entry in the resource table that points to freed memory.

create_resource_iosurface:
  kalloc(0x100) → obj          ; IOGPUSysMemory allocated
  table[new_id] = obj           ; registered with a reference
  ADDS w_result, w_width, w_height
  b.hs error_path               ; ← overflow: jumps here
error_path:
  ; object NOT released, table entry NOT cleared
  return kIOReturnInvalid

The stale table entry persists until the same resource ID is reused or the device is closed.

UAF Dereference

IOGPUDevice::set_resource_purgeable(id) looks up the stale ID via get_resource_by_id(), finds the dangling entry, and accesses it non-virtually:

PoC Behaviour

The PoC triggers the UAF using Metal's newTextureWithDescriptor:iosurface:plane: with crafted overflow dimensions. Before the UAF dereference:

• 768× (0x300) MTLBuffer(0x100, StorageModeShared) sprayed to fill the freed kalloc.256 slot
• Spray data sets [+0x10]=0, [+0x24]=0, [+0x28]=0 → Call2 and Call3 are safely skipped
• UAF dereference proceeds on attacker-controlled heap memory

Trigger detection: set_resource_purgeable on a nonexistent resource returns 0xe00002c2. After the UAF + spray reclaims the slot, the same call returns 0xe0002be (resource found, Call1 fired) — confirming the stale entry is being processed with our spray data.

iOS 26 Exploitation Notes

Zone sequestration in iOS 26 places freed IOGPUSysMemory objects back into a type-stable zone free list. Both [obj+0x10] (IOMemoryDescriptor) and [obj+0x18] (IOGPUDevice) hold external retain counts and remain live after the object is freed. As a result, completeMemory() always executes on valid ivar data — the UAF dereference is confirmed but a kernel r/w primitive via this path alone is blocked on iOS 26 without a secondary primitive to break zone sequestration.

Requirements

• iOS 26.6 (23G71) or earlier
• Apple A-series GPU (tested: A14 Bionic, iPhone 12)
• No entitlements required — reachable from any Metal-capable sandboxed app

Build

clang -arch arm64 -framework Metal -framework IOSurface \
      -framework IOKit -framework Foundation \
      -o poc poc/poc_iogpu_uaf.m

Or open in Xcode, set a valid signing team, and run on device.

Timeline

References

• Apple Security Advisory — iOS 26.6.1
• Full Disclosure post