---
id: CVE-2026-99270
title: 'tcp: Fix potential UAF in reqsk_timer_handler().'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  tcp: Fix potential UAF in reqsk_timer_handler().

  When TCP socket migration fails at inet_ehash_insert() in
  reqsk_timer_handler(), we jump to the no_ownership: label
  an…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 83fccfc3940c4a2db90fd7e7079f5b465cd8c6af <
    97c8a3c1f73d828de43a5a88e8a9a143efb2b661
  - Linux d3a1196bfc462943694623412d8e03aaf172bdc1
  - Linux >= 4.1.11 < 4.2
  - Linux 4.2
published: '2026-11-03'
updated: '2026-11-03'
sourceUpdated: '2026-11-03T19:14:43.225Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-99270'
references:
  - url: 'https://git.kernel.org/stable/c/97c8a3c1f73d828de43a5a88e8a9a143efb2b661'
tags:
  - cve.org
epss: 0.0031
epssPercentile: 0.2397
ingestedAt: '2026-11-05T20:33:06.393Z'
---

## Overview

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

tcp: Fix potential UAF in reqsk_timer_handler().

When TCP socket migration fails at inet_ehash_insert() in
reqsk_timer_handler(), we jump to the no_ownership: label
and free the new reqsk immediately with __reqsk_free().

Thus, we must stop the new reqsk's timer before jumping to the
label, but the timer might be missed since the cited commit,
resulting in UAF.

As we are in the original reqsk's timer context, we can safely
call timer_delete_sync() for the new reqsk.

Let's pass false to __inet_csk_reqsk_queue_drop() to stop
the new reqsk's timer.

## Affected

- `Linux >= 83fccfc3940c4a2db90fd7e7079f5b465cd8c6af < 97c8a3c1f73d828de43a5a88e8a9a143efb2b661`
- `Linux d3a1196bfc462943694623412d8e03aaf172bdc1`
- `Linux >= 4.1.11 < 4.2`
- `Linux 4.2`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.