Deleting a user-mode module thread leaks its privileged kernel stack

Summary

One logical thread of a user-mode ThreadX module costs the Module Manager's shared object pool two allocations, not one. The module asks for a `TX_THREAD` control block through `txm_module_object_allocate`; `_txm_module_manager_thread_create` then takes a second allocation of `TXM_MODULE_KERNEL_STACK_SIZE` bytes for the privileged kernel stack that thread's system calls run on, and records it in the control block. Both come from `_txm_module_manager_object_pool` and both are linked onto the module's allocation list. The Module Manager's thread-delete dispatcher released only the first. The kernel stack stayed allocated until the whole module was stopped, so a module that creates, terminates and deletes threads in a loop — every state transition valid, every service returning `TX_SUCCESS` — removed a fixed block from a finite pool shared by the manager and by every other loaded module, on every cycle, for as long as it stayed loaded. Once the pool is exhausted, no memory-protected module can create any kernel object and no user-mode module thread can be created anywhere in the system. Vulnerable function: `_txm_module_manager_tx_thread_delete_dispatch`, in `common_modules/module_manager/inc/txm_module_manager_dispatch.h`.

Timeline

1. Oct 20, 2026, 3:19 PM UTCCVE published
2. Oct 20, 2026, 5:05 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 20, 2026, 5:06 PM UTCRecord last updated
4. Oct 22, 2026, 9:34 PM UTCFirst seen by cve.now

Affected versions

• ThreadX

  From 6.0.1 · through 6.5.1.202602a

References 1