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CVE-2026-31557
nvmet: move async event work off nvmet-wq
Published 2026-04-24 (6 months ago) by the Linux kernel CNA. Subsystem drivers/nvme. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-31557 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixedDSA-6238-1 · 2026-04-30 · text | 6.12.85-1 | Update the kernel and reboot. DSA-6238-1 shipped the fix on 2026-04-30, in 6.12.85-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 6.19.11-1 | Update the kernel and reboot. Fixed in 6.19.11-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.19.11-1 | Update the kernel and reboot. Fixed in 6.19.11-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
For target nvmet_ctrl_free() flushes ctrl->async_event_work. If nvmet_ctrl_free() runs on nvmet-wq, the flush re-enters workqueue completion for the same worker:- A. Async event work queued on nvmet-wq (prior to disconnect): nvmet_execute_async_event() queue_work(nvmet_wq, &ctrl->async_event_work) nvmet_add_async_event() queue_work(nvmet_wq, &ctrl->async_event_work) B. Full pre-work chain (RDMA CM path): nvmet_rdma_cm_handler() nvmet_rdma_queue_disconnect() __nvmet_rdma_queue_disconnect() queue_work(nvmet_wq, &queue->release_work) process_one_work() lock((wq_completion)nvmet-wq) <--------- 1st nvmet_rdma_release_queue_work() C. Recursive path (same worker): nvmet_rdma_release_queue_work() nvmet_rdma_free_queue() nvmet_sq_destroy() nvmet_ctrl_put() nvmet_ctrl_free() flush_work(&ctrl->async_event_work) __flush_work() touch_wq_lockdep_map() lock((wq_completion)nvmet-wq) <--------- 2nd Lockdep splat: ============================================ WARNING: possible recursive locking detected 6.19.0-rc3nvme+ #14 Tainted: G N -------------------------------------------- kworker/u192:42/44933 is trying to acquire lock: ffff888118a00948 ((wq_completion)nvmet-wq){+.+.}-{0:0}, at: touch_wq_lockdep_map+0x26/0x90 but task is already holding lock: ffff888118a00948 ((wq_completion)nvmet-wq){+.+.}-{0:0}, at: process_one_work+0x53e/0x660 3 locks held by kworker/u192:42/44933: #0: ffff888118a00948 ((wq_completion)nvmet-wq){+.+.}-{0:0}, at: process_one_work+0x53e/0x660 #1: ffffc9000e6cbe28 ((work_completion)(&queue->release_work)){+.+.}-{0:0}, at: process_one_work+0x1c5/0x660 #2: ffffffff82d4db60 (rcu_read_lock){....}-{1:3}, at: __flush_work+0x62/0x530 Workqueue: nvmet-wq nvmet_rdma_release_queue_work [nvmet_rdma] Call Trace: __flush_work+0x268/0x530 nvmet_ctrl_free+0x140/0x310 [nvmet] nvmet_cq_put+0x74/0x90 [nvmet] nvmet_rdma_free_queue+0x23/0xe0 [nvmet_rdma] nvmet_rdma_release_queue_work+0x19/0x50 [nvmet_rdma] process_one_work+0x206/0x660 worker_thread+0x184/0x320 kthread+0x10c/0x240 ret_from_fork+0x319/0x390 Move async event work to a dedicated nvmet-aen-wq to avoid reentrant flush on nvmet-wq.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/nvme/target/admin-cmd.c
drivers/nvme/target/core.c
drivers/nvme/target/nvmet.h
drivers/nvme/target/rdma.c
- What this is
- NVM EXPRESS TARGET DRIVERMAINTAINERS section matched on drivers/nvme/target/ · linux-nvme@lists.infradead.org · Supported
- Kernel module
- nvmet
Check it on the machine
grep -w CONFIG_NVME_TARGET /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w nvmetPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sidm
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switch
- CONFIG_NVME_TARGET
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-04-24 (6 months ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.63%, higher than 49.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/nvme
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.18 | 6.12.80 | 49c7c50ee632 |
| 5.18 | 6.18.21 | ca111c9d8d6c |
| 5.18 | 6.19.11 | 25ceffc1dabe |
| 5.18 | 7.0 | 2922e3507f6d |
| 5.15.42 | 0 | 0 |
| 5.17.10 | 0 | 0 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DSA-6238-1 | 2026-04-30 | trixie 6.12.85-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- The vulnerable async event and teardown path is reachable through NVMe-oF target networking, including nvmet-tcp, by connecting to the target, issuing an admin Async Event Request, and disconnecting.
- AC:LAttack complexity, low
- The attacker controls both relevant actions: queuing async event work and triggering connection teardown. No uncontrollable memory layout or victim timing condition is required beyond repeating the network sequence.
- PR:NPrivileges required, none
- The NVMe discovery controller is reachable with the standard discovery NQN, allows hosts by design, supports async event requests, and skips DH-HMAC-CHAP authentication. In an exposed nvmet-tcp deployment this is reachable without credentials.
- UI:NUser interaction, none
- No victim user action is needed after the target service is exposed. The remote peer can trigger the sequence by protocol messages and disconnecting.
- S:UScope, unchanged
- The impact is confined to the kernel/NVMe target host that processes the malicious connection. It does not cross a VM, IOMMU, or separate security authority boundary.
- C:NConfidentiality impact, none
- The bug is a workqueue/flush recursion issue and does not expose kernel memory or target data. There is no identified read primitive.
- I:NIntegrity impact, none
- The issue does not corrupt memory or provide a write/control-flow primitive. It affects teardown/workqueue progress rather than data integrity.
- A:HAvailability impact, high
- The recursive workqueue flush can trigger a kernel lockdep warning and can lead to a panic or teardown hang in hardened/debug configurations. It can be triggered repeatedly over the network, so availability impact is scored high.