CVE-2026-33104
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Win32K - GRFX allows an authorized at
CVSS
7.0
High
EPSS
0.2%
p11
KEV
—
Exploit Today
3
0-100
Published: Apr 14, 2026 · Last modified: Jul 24, 2026 · CWE-362 · CWE-416
0.2%EPSS · 30 days0.2%
2026-07-172026-08-13
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Win32K - GRFX allows an authorized attacker to elevate privileges locally.
CVECVSSEPSSKEVRExploitTitleMod.
CVE-2026-123668.8 HIG—
———Zephyr's dynamic kernel-object disposal path unref_check() in kernel/userspace/userspace.c frees an object's storage (k_free(dyn->data)) once its reference count reaches zero, after running a per-object-type cleanup. The cleanup switch handled only K_OBJ_MSGQ and K_OBJ_STACK; there was no K_OBJ_TIMER case. A dynamically-allocated, initialized, and armed k_timer keeps its embedded struct _timeout dnode linked in the global timeout queue (_timeout_q), so freeing the timer storage without cancelling the timeout leaves a dangling node in that queue.
When the timer next expires, the timeout machinery walks _timeout_q and invokes z_timer_expiration_handler() on the freed node, dereferencing and writing freed (and reusable) kernel heap in kernel/ISR context. This is a deterministic use-after-free that does not depend on SMP: the queued node is simply never unlinked at free time.
The disposal is reachable from an unprivileged user thread under CONFIG_USERSPACE + CONFIG_DYNAMIC_OBJECTS: a thread that holds the last permission on such a timer drops it via the k_object_release() syscall (or by exiting, through k_thread_perms_all_clear()), and can arm the timer itself via the k_timer_start() syscall. The free and the expiration handler run at kernel privilege while the actor is a user thread, so the bug is a sandbox-escape memory-corruption primitive usable for privilege escalation. The fix adds k_timer_cleanup() (cancel the timeout and wait for any in-flight handler) and calls it for K_OBJ_TIMER before freeing.8hCVE-2026-123655.8 MED—
———A use-after-free exists in the Zephyr second-generation work queue (kernel/work.c) in the handling of delayable work timeouts. When a delayable work item's timeout has been dequeued and its handler work_timeout() is in flight (blocked acquiring the work-queue spinlock), a concurrent cancellation does not wait for that handler to finish. In unschedule_locked() the pre-fix code called z_abort_timeout(), which for an already-announcing record returns -EINVAL without removing it; cancel_async_locked() then observes the work as idle, so even k_work_cancel_delayable_sync() and k_work_flush_delayable() return without blocking on the in-flight handler.
Because those are the APIs the kernel header documents as the safe way to cancel before freeing a k_work_delayable, a caller that frees the object immediately after a successful sync cancel can race the still-pending handler. work_timeout() subsequently dereferences the freed record: it reads to->dticks via z_is_timeout_handler_canceled() and, if the freed slot has been reused so the bail check fails, performs a read-modify-write of wp->flags (K_WORK_DELAYED_BIT) and submits work against a stale dw->queue pointer — a use-after-free read and write.
The k_work API is kernel-mode only (no __syscall entry point), so this is a kernel-internal concurrency defect rather than a userspace privilege escalation. Triggering it requires an SMP build and a subsystem that schedules and then frees (or reschedules) a delayable work item in the narrow window while its timeout is announcing; an attacker able to influence the timing of such teardown (for example via connection churn driving subsystem timers) has a plausible but probabilistic path. The impact is kernel memory corruption or crash (denial of service).
The fix makes unschedule_locked() wait, by spinning on z_try_abort_timeout() returning -EAGAIN while releasing and re-acquiring the work spinlock, until any in-flight handler completes before returning, and switches work_timeout() to atomic K_WORK_DELAYED_BIT ownership. This closes both the free-then-handler use-after-free and the related reschedule early-fire race.8hCVE-2026-13198——
———Nozomi Networks Labs identified a CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the event notification functionality of KUNBUS piControl in version 2.6.2 that allows a local authenticated attacker to corrupt kernel heap and event-list state and disclose a small amount of adjacent kernel memory, resulting in kernel memory corruption and denial of service, by issuing concurrent crafted requests from multiple threads through the piControl character device.8hCVE-2026-13197——
———Nozomi Networks Labs identified a CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the configuration and process-image management functionality of KUNBUS piControl in version 2.6.2 that allows a local authenticated attacker to trigger use-after-free and invalid pointer dereferences on kernel configuration objects, resulting in kernel memory corruption and denial of service, by issuing concurrent crafted requests through the piControl character device.8hCVE-2026-73557——
———vLLM is an inference and serving engine for large language models. From 0.20.2rc0 until 0.26.0, safe_load_prompt_embeds in vllm/renderers/embed_utils.py uses torch.sparse.check_sparse_tensor_invariants, whose process-global save, enable, and restore state can be raced by concurrent prompt_embeds parts submitted to POST /v1/chat/completions through AsyncMultiModalItemTracker.resolve_items, asyncio.gather, and the default executor, allowing an invalid sparse tensor to reach tensor.to_dense despite the CVE-2025-62164 guard when enable_prompt_embeds is enabled. This issue is fixed in version 0.26.0.1dCVE-2026-0295—0.3%
——0A race condition in the Palo Alto Networks GlobalProtect™ client on macOS enables a locally authenticated low-privileged attacker to escalate their privileges to root.
The GlobalProtect app on Linux, Windows, iOS, Android, and Chrome OS is not affected.2d