---
id: CVE-2025-39963
title: >-
  kernel: io_uring: fix incorrect io_kiocb reference in io_link_skb
  (CVE-2025-39963)
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  io_uring: fix incorrect io_kiocb reference in io_link_skb

  In io_link_skb function, there is a bug where prev_notif is incorrectly
  assigned using 'nd' instead of 'prev_nd…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cvssSource: vendor
cwe: CWE-1025
vendor: Red Hat
product: Red Hat Enterprise Linux 9
affected:
  - enterprise_linux 10
  - enterprise_linux 9
published: '2025-10-09'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T23:24:05+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39963.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39963.json
  - url: 'https://access.redhat.com/security/cve/CVE-2025-39963'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2402718'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2025-39963'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-39963'
  - url: >-
      https://lore.kernel.org/linux-cve-announce/2025100917-CVE-2025-39963-b0ff@gregkh/T
  - url: 'https://git.kernel.org/stable/c/a89c34babc2e5834aa0905278f26f4dbe4b26b76'
  - url: 'https://git.kernel.org/stable/c/50a98ce1ea694f1ff8e87bc2f8f84096d1736f6a'
  - url: 'https://git.kernel.org/stable/c/2c139a47eff8de24e3350dadb4c9d5e3426db826'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
  - score-dispute
epss: 0.00152
epssPercentile: 0.0432
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-15T21:55:14.622512Z'
scores:
  vendor: 5.5
  cna: 7.8
ingestedAt: '2026-10-15T22:48:25.532Z'
---

## Overview

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

io_uring: fix incorrect io_kiocb reference in io_link_skb

In io_link_skb function, there is a bug where prev_notif is incorrectly
assigned using 'nd' instead of 'prev_nd'. This causes the context
validation check to compare the current notification with itself instead
of comparing it with the previous notification.

Fix by using the correct prev_nd parameter when obtaining prev_notif.

## Vendor advisories

- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39963.json)

**kernel: io_uring: fix incorrect io_kiocb reference in io_link_skb** — rated Low by Red Hat. Released 2025-10-09, updated 2026-10-16.

Affected:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 9

No fix planned:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 9

Not affected:

- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8

## Remediation

Fix deferred

Workarounds / mitigations:

- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.