---
id: CVE-2023-53600
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  tunnels: fix kasan splat when generating ipv4 pmtu error

  If we try to emit an icmp error in response to a nonliner skb, we get

  BUG: KASAN: slab-out-of-bounds in ip_co…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  tunnels: fix kasan splat when generating ipv4 pmtu error

  If we try to emit an icmp error in response to a nonliner skb, we get

  BUG: KASAN: slab-out-of-bounds in ip_co…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cwe:
  - CWE-125
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.9, < 5.10.191'
  - 'linux_kernel >= 5.11, < 5.15.127'
  - 'linux_kernel >= 5.16, < 6.1.46'
  - 'linux_kernel >= 6.2, < 6.4.11'
  - linux_kernel = 6.5
patched:
  - linux_kernel 6.4.11
published: '2025-10-04'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:17:43.897'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2023-53600'
references:
  - url: 'https://git.kernel.org/stable/c/5850c391fd7e25662334cb3cbf29a62bcbff1084'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6a7ac3d20593865209dceb554d8b3f094c6bd940'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/da5f42a6e7485fbb7a6dbd6a2b3045e19e4df5cc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e95808121953410db8c59f0abfde70ac0d34222c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fe6a9f7516735be9fdabab00e47ef7a3403a174d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.00297
epssPercentile: 0.22226
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-15T21:35:49.694567Z'
ingestedAt: '2026-10-15T22:48:25.411Z'
---

## Overview

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

tunnels: fix kasan splat when generating ipv4 pmtu error

If we try to emit an icmp error in response to a nonliner skb, we get

BUG: KASAN: slab-out-of-bounds in ip_compute_csum+0x134/0x220
Read of size 4 at addr ffff88811c50db00 by task iperf3/1691
CPU: 2 PID: 1691 Comm: iperf3 Not tainted 6.5.0-rc3+ #309
[..]
 kasan_report+0x105/0x140
 ip_compute_csum+0x134/0x220
 iptunnel_pmtud_build_icmp+0x554/0x1020
 skb_tunnel_check_pmtu+0x513/0xb80
 vxlan_xmit_one+0x139e/0x2ef0
 vxlan_xmit+0x1867/0x2760
 dev_hard_start_xmit+0x1ee/0x4f0
 br_dev_queue_push_xmit+0x4d1/0x660
 [..]

ip_compute_csum() cannot deal with nonlinear skbs, so avoid it.
After this change, splat is gone and iperf3 is no longer stuck.

## Affected

- `linux_kernel >= 5.9, < 5.10.191`
- `linux_kernel >= 5.11, < 5.15.127`
- `linux_kernel >= 5.16, < 6.1.46`
- `linux_kernel >= 6.2, < 6.4.11`
- `linux_kernel = 6.5`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.4.11`