---
id: "CVE-2026-98723"
kind: "vulnerability"
aliases: ["CVE-2026-98723"]
title: "Linux kernel NVMe target: Preempt and Abort skips in-flight I/O"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["kernel", "linux", "nvme-target", "other", "self-hosted"]
not_affected_if: ["nvme-target-not-in-use"]
published_at: "2026-10-18T16:17:25+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:17:21+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98723", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel NVMe target: Preempt and Abort skips in-flight I/O

The Linux kernel NVMe target stores a nil host UUID in reservation references, so the Preempt and Abort path never matches the victim host. The preempting host sees success while the victim's in-flight I/O keeps running.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98723

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

nvmet: copy the hostid into the ctrl before creating PR pc_refs

Commit 6202783184bf ("nvmet: Improve nvmet_alloc_ctrl() interface and
implementation") added a second uuid_copy() of args->hostid near the end
of nvmet_alloc_ctrl(), and commit 7b658153f1b8 ("nvmet: Remove duplicate
uuid_copy") removed the original copy that sat before
nvmet_ctrl_init_pr() instead of the new one.

Since then nvmet_ctrl_init_pr() snapshots ctrl->hostid into the
per-controller per-namespace reservation refs while the uuid_copy()
from the connect data runs later, after the controller is published.
The ctrl is allocated with kzalloc(), so every pc_ref created on this
path stores the nil UUID.

pc_ref->hostid has a single consumer: nvmet_pr_set_ctrl_to_abort()
matches it against the preempted registrant's hostid to kill and drain
the victim's in-flight I/O for Preempt and Abort.  The match can never
hit with the nil UUID, so whenever a namespace with reservations
enabled exists before a host connects, which includes every reconnect,
Preempt and Abort silently degrades into a plain Preempt: the
preempting host sees success while the victim's in-flight I/O is still
in the air.

Copy the hostid where the rest of the connect data is consumed, before
the controller is published and before nvmet_ctrl_init_pr() takes its
snapshot.

---

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