EUVD-2026-66504
GHSA-rf5w-wp84-mh25
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Local kernel path (AV:L) gated by a hard-to-win probe-failure/reset race (AC:H) needing local privilege to drive storage (PR:L); impact is a use-after-free crash/corruption, primarily availability (A:H).
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
5DescriptionCVE.org
In the Linux kernel, the following vulnerability has been resolved:
block: stop the timeout timer when releasing a never added disk
disk_release() undoes blk_mq_init_allocated_queue() for a disk whose probe failed before add_disk(), but it only calls blk_mq_exit_queue(). Nothing there stops q->timeout, and that timer rolls forward: it stays pending until it next expires, not until the last request completes. So if the driver issued any I/O before adding the disk, the request_queue is freed while still linked into a timer wheel bucket.
Commit 6f8191fdf41d ("block: simplify disk shutdown") dropped the blk_cleanup_queue() call that used to stop it. __del_gendisk() and blk_mq_destroy_queue() still do; only the probe failure path lost it.
nvme gets there because nvme_update_ns_info() submits Report Zones or FDP io-mgmt-recv on ns->queue before the disk is added, so a later failure - a concurrent reset setting NVME_CTRL_FROZEN, or device_add_disk() failing - lands in put_disk() with the timer armed:
BUG: KASAN: slab-use-after-free in detach_if_pending+0x30c/0x340 Write of size 8 at addr ffff888004d71310 by task kworker/u8:2/37 __timer_delete_sync+0x156/0x240 kernel/time/timer.c:1621 blk_sync_queue+0x22/0x40 block/blk-core.c:222 nvme_sync_queues+0x100/0x150 drivers/nvme/host/core.c:5362 nvme_reset_work+0x138/0x930 drivers/nvme/host/pci.c:3264
Allocated by task 34: __blk_mq_alloc_disk+0x33/0x100 block/blk-mq.c:4462 nvme_alloc_ns+0x290/0x3870 drivers/nvme/host/core.c:4146
Freed by task 0: blk_free_queue_rcu+0x3a/0x50 block/blk-core.c:254 rcu_core+0xc10/0x1730 kernel/rcu/tree.c:2857
The queue being synced there is ctrl->admin_q, only a victim sharing a timer wheel bucket with the freed queue's dangling entry; other runs tripped in enqueue_timer(), __run_timers() or blk_mq_timeout_work(). Failing nvme_alloc_ns() with a debug patch makes it deterministic: one leaked timer trips KASAN within seconds, while 1987 patched releases produced no splat.
Stop the timer and the queue work items before blk_mq_exit_queue(), like blk_mq_destroy_queue() does.
Found by FuzzNvme.
AnalysisAI
Use-after-free in the Linux kernel block layer occurs when a disk whose driver probe fails before add_disk() is released: disk_release() calls blk_mq_exit_queue() without stopping the request_queue timeout timer, so the request_queue is freed while still linked in a timer-wheel bucket. NVMe reaches this path because nvme_update_ns_info() issues Report Zones or FDP io-mgmt-recv I/O on the namespace queue before the disk is added, and a later failure (concurrent reset setting NVME_CTRL_FROZEN, or device_add_disk() failing) leaves the timer armed on freed memory. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a driver that submits I/O on a request_queue before add_disk() and then fails the probe; in practice this is the NVMe driver, where nvme_update_ns_info() sends Report Zones (zoned namespaces) or FDP io-mgmt-recv on ns->queue prior to disk addition. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The supplied CVSS 9.8 (AV:N/AC:L/PR:N/UI:N, C:H/I:H/A:H) is an automated NVD-style score and materially overstates real-world risk - this defect is not remotely reachable. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A local attacker or fault condition induces an NVMe namespace probe to issue I/O (Report Zones or FDP io-mgmt-recv) and then fail before the disk is added - for example by racing a controller reset that sets NVME_CTRL_FROZEN. The request_queue is freed with its timeout timer still armed in a timer-wheel bucket, and the next timer operation writes to freed memory, causing a use-after-free that manifests as a kernel crash (DoS) or potential memory corruption. … |
| Remediation | Upgrade to a kernel containing the fix, which stops q->timeout and flushes the queue work items before blk_mq_exit_queue() in the probe-failure release path, matching blk_mq_destroy_queue(). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: identify all Linux systems equipped with NVMe storage using your asset inventory and current configuration management tools; correlate with known affected kernel versions from the vendor advisory. …
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