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VulnerabilityAwaiting classification

CVE-2025-40261

CRITICAL · 9.8 CVSS v3.1 Published 2025-12-04
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: nvme: nvme-fc: Ensure ->ioerr_work is cancelled in nvme_fc_delete_ctrl() nvme_fc_delete_assocation() waits for pending I/O to complete before returning, and an error can cause ->ioerr_work to be queued after cancel_work_sync() had been called. Move the call to cancel_work_sync() to be after nvme_fc_delete_association() to ensure ->ioerr_work is not running when the nvme_fc_ctrl object is freed. Otherwise the following can occur: [ 1135.911754] list_del corruption, ff2d24c8093f31f8->next is NULL [ 1135.917705] ------------[ cut here ]------------ [ 1135.922336] kernel BUG at lib/list_debug.c:52! [ 1135.926784] Oops: invalid opcode: 0000 [#1] SMP NOPTI [ 1135.931851] CPU: 48 UID: 0 PID: 726 Comm: kworker/u449:23 Kdump: loaded Not tainted 6.12.0 #1 PREEMPT(voluntary) [ 1135.943490] Hardware name: Dell Inc. PowerEdge R660/0HGTK9, BIOS 2.5.4 01/16/2025 [ 1135.950969] Workqueue: 0x0 (nvme-wq) [ 1135.954673] RIP: 0010:__list_del_entry_valid_or_report.cold+0xf/0x6f [ 1135.961041] Code: c7 c7 98 68 72 94 e8 26 45 fe ff 0f 0b 48 c7 c7 70 68 72 94 e8 18 45 fe ff 0f 0b 48 89 fe 48 c7 c7 80 69 72 94 e8 07 45 fe ff <0f> 0b 48 89 d1 48 c7 c7 a0 6a 72 94 48 89 c2 e8 f3 44 fe ff 0f 0b [ 1135.979788] RSP: 0018:ff579b19482d3e50 EFLAGS: 00010046 [ 1135.985015] RAX: 0000000000000033 RBX: ff2d24c8093f31f0 RCX: 0000000000000000 [ 1135.992148] RDX: 0000000000000000 RSI: ff2d24d6bfa1d0c0 RDI: ff2d24d6bfa1d0c0 [ 1135.999278] RBP: ff2d24c8093f31f8 R08: 0000000000000000 R09: ffffffff951e2b08 [ 1136.006413] R10: ffffffff95122ac8 R11: 0000000000000003 R12: ff2d24c78697c100 [ 1136.013546] R13: fffffffffffffff8 R14: 0000000000000000 R15: ff2d24c78697c0c0 [ 1136.020677] FS: 0000000000000000(0000) GS:ff2d24d6bfa00000(0000) knlGS:0000000000000000 [ 1136.028765] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1136.034510] CR2: 00007fd207f90b80 CR3: 000000163ea22003 CR4: 0000000000f73ef0 [ 1136.041641] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 1136.048776] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 [ 1136.055910] PKRU: 55555554 [ 1136.058623] Call Trace: [ 1136.061074] <TASK> [ 1136.063179] ? show_trace_log_lvl+0x1b0/0x2f0 [ 1136.067540] ? show_trace_log_lvl+0x1b0/0x2f0 [ 1136.071898] ? move_linked_works+0x4a/0xa0 [ 1136.075998] ? __list_del_entry_valid_or_report.cold+0xf/0x6f [ 1136.081744] ? __die_body.cold+0x8/0x12 [ 1136.085584] ? die+0x2e/0x50 [ 1136.088469] ? do_trap+0xca/0x110 [ 1136.091789] ? do_error_trap+0x65/0x80 [ 1136.095543] ? __list_del_entry_valid_or_report.cold+0xf/0x6f [ 1136.101289] ? exc_invalid_op+0x50/0x70 [ 1136.105127] ? __list_del_entry_valid_or_report.cold+0xf/0x6f [ 1136.110874] ? asm_exc_invalid_op+0x1a/0x20 [ 1136.115059] ? __list_del_entry_valid_or_report.cold+0xf/0x6f [ 1136.120806] move_linked_works+0x4a/0xa0 [ 1136.124733] worker_thread+0x216/0x3a0 [ 1136.128485] ? __pfx_worker_thread+0x10/0x10 [ 1136.132758] kthread+0xfa/0x240 [ 1136.135904] ? __pfx_kthread+0x10/0x10 [ 1136.139657] ret_from_fork+0x31/0x50 [ 1136.143236] ? __pfx_kthread+0x10/0x10 [ 1136.146988] ret_from_fork_asm+0x1a/0x30 [ 1136.150915] </TASK>

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A race condition in the Linux kernel's NVMe over Fabrics FC driver (nvme-fc) allows the ioerr_work workqueue to be queued after cancel_work_sync() has been called during controller deletion, leading to list_del corruption and a kernel BUG when the workqueue tries to access freed memory. The fix requires reordering cancel_work_sync() to execute after nvme_fc_delete_association() completes.

MitigationApply the kernel patch that moves cancel_work_sync() after nvme_fc_delete_association() in nvme_fc_delete_ctrl(). This is a kernel-level fix requiring a kernel update or patch deployment.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify kernel version
    Run 'uname -r' to obtain the running kernel version
    Affected if Kernel version is within the vulnerable range for this CVE and the system uses NVMe over Fabrics
  2. Confirm nvme-fc driver presence
    Check if the nvme-fc driver is loaded: run 'lsmod | grep nvme_fc' or inspect /sys/module/nvme_fc/
    Affected if The nvme_fc kernel module is loaded
  3. Detect active NVMe-FC controllers
    List NVMe Fabrics controllers: check /sys/class/nvme-fabrics/ or run 'nvme list-subsys' if available
    Affected if Any NVMe over Fibre Channel (nvme-fc) controllers are configured or connected
  4. Inspect for crash artifacts
    Review kernel logs: run 'dmesg' or check /var/log/kern.log for use-after-free, list_del corruption, or kernel panics referencing nvme_fc_ctrl or ioerr_work
    Affected if Crash logs show the specific use-after-free or list_del corruption pattern described in this CVE

Environment is affected if running a vulnerable kernel version with the nvme-fc driver loaded and active NVMe-FC controllers present, or if crash logs show the characteristic use-after-free behavior.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the kernel patch that moves cancel_work_sync() after nvme_fc_delete_association() in nvme_fc_delete_ctrl(). This is a kernel-level fix requiring a kernel update or patch deployment.

Recommended fix Moderate confidence

Linux kernel 6.12.0 or later (the fix was applied to the mainline kernel; check distribution-specific security advisories for backported patches)

  1. Identify the current Linux kernel version using `uname -r`
  2. Check if the distribution provides security updates or check the kernel changelog for CVE-2025-40261
  3. Upgrade the Linux kernel to a version that includes the fix. The fix is a code change in drivers/nvme/host/fc.c that reorders cancel_work_sync() to be called after nvme_fc_delete_association()
  4. After kernel upgrade, reboot the system to load the fixed kernel
  5. Verify the running kernel version includes the fix by checking the nvme-fc driver code in /drivers/nvme/host/fc.c or the kernel release notes
Caveat Major kernel upgrades may require system downtime and could affect proprietary kernel modules or drivers

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing8.0 h
  • Review / QA3.0 h
14.0 hours of engineering $2,320
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-40261 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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