{"id":"CVE-2026-11742","title":"Use-after-free race in kernel `k_queue_peek_head/tail` due to missing spinlock","summary":"The kernel queue helper z_queue_node_peek() in kernel/queue.c dereferences a node taken from a queue's data_q list, reading the node's flag byte and, for items enqueued via k_queue_alloc_append/alloc_prepend, the data pointer of an inter…","severity":"low","cvss":3.6,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L","cvssSource":"cna","cwe":["CWE-416"],"vendor":"zephyrproject","product":"zephyr","affected":["zephyr >= 1.12.0 < 4.3.2","zephyr >= 4.4.0 < 4.4.2"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-08-10T16:57:12.229945Z"},"published":"2026-08-07","updated":"2026-11-04","sourceUpdated":"2026-11-04T04:59:10.924Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-11742","references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/a6b6149a50cb0f64061869f7536acbf80ccc5e0c","label":"Fix commit"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-8xm3-4w69-29mm","label":"GHSA-8xm3-4w69-29mm"}],"tags":["cve.org"],"epss":0.00127,"epssPercentile":0.02415,"ingestedAt":"2026-11-05T20:33:06.697Z","slug":"CVE-2026-11742","body":"## Overview\n\nThe kernel queue helper z_queue_node_peek() in kernel/queue.c dereferences a node taken from a queue's data_q list, reading the node's flag byte and, for items enqueued via k_queue_alloc_append/alloc_prepend, the data pointer of an internally allocated alloc_node struct. The implementations of z_impl_k_queue_peek_head() and z_impl_k_queue_peek_tail() performed this read-and-dereference without holding the queue's spinlock, while every other accessor of the same list — including k_queue_get(), which unlinks a node and k_free()s its backing alloc_node — operates under that lock.\n\nBecause peek was unsynchronized, a concurrent k_queue_get() on the same queue (on an SMP build, or under preemption/ISR concurrency) can free the node between the moment peek obtains the node pointer and the moment it dereferences it. The peek then reads flag bits and a data pointer out of freed, potentially re-allocated heap memory and returns a stale or dangling pointer to its caller. k_fifo and k_lifo are thin wrappers over k_queue, so this affects buffer queues used throughout the net_buf, Bluetooth, USB, and networking subsystems; the peek operations are also system calls reachable from CONFIG_USERSPACE threads.\n\nThe consequences are a use-after-free read that can leak stale heap contents (one pointer word) and, when the returned dangling pointer is subsequently consumed as a live buffer, a dereference that can crash the system or corrupt memory. Exploitation requires winning a small race window with local access (e.g. a userspace process racing k_queue_peek_* against k_queue_get on a shared queue, or two CPUs), so practical impact is bounded and of low severity.\n\nThe fix wraps both peek implementations with k_spin_lock/k_spin_unlock on the queue lock, making the read-and-dereference atomic with respect to the concurrent unlink-and-free and bringing peek into line with the rest of the queue's locking discipline.\n\n## Affected\n\n- `zephyr >= 1.12.0 < 4.3.2`\n- `zephyr >= 4.4.0 < 4.4.2`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":20,"depthScoreParts":{"impact":19.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}