---
id: CVE-2026-71971
title: >-
  U-Boot before 2026.10-rc3 with CONFIG_IP_DEFRAG enabled contains an
  out-of-bounds write vulnerability in the __net_defragment() function in
  net/net.c
summary: >-
  U-Boot before 2026.10-rc3 with CONFIG_IP_DEFRAG enabled contains an
  out-of-bounds write vulnerability in the __net_defragment() function in
  net/net.c. Remote attackers can send a crafted IP fragment with non-zero
  offset and More-Fragment…
severity: high
cvss: 8.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H'
cwe:
  - CWE-787
vendor: u-boot
product: u-boot
affected:
  - u-boot < 2026.10-rc3
published: '2026-09-29'
updated: '2026-09-29'
sourceUpdated: '2026-09-29T22:18:21.723'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-71971'
references:
  - url: 'https://github.com/u-boot/u-boot'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/u-boot/u-boot/blob/v2026.07/net/net.c#L975'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/u-boot/u-boot/commit/04ca915d5bf39dda5d1bce62d04d2b59d293c5b9
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/u-boot-before-2026.10-rc3-out-of-bounds-write-in-ip-fragment-reassembly
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-29T21:49:08.269Z'
---

## Overview

U-Boot before 2026.10-rc3 with CONFIG_IP_DEFRAG enabled contains an out-of-bounds write vulnerability in the __net_defragment() function in net/net.c. Remote attackers can send a crafted IP fragment with non-zero offset and More-Fragments flag set during netboot to corrupt adjacent memory and crash the bootloader.

## Remediation

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