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VulnerabilityPublished Updated

CVE-2026-71971: 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

Affects u-bootSource GCVE Database

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Not known to be exploited · CVSS 8.2 High · fixed in 2026.10-rc3 : patch u-boot soon.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2026.10-rc3, 2016.01+dfsg1-2ubuntu5+esm1, 2020.10+dfsg-1ubuntu0~18.04.3+esm1 +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 29 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
GitHubu-boot/u-bootpkg:github/u-boot/u-bootOther threatsAffected
  • <2026.10-rc3
Fixed in
  • 2026.10-rc3
Ubuntu Pro 16.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=esm-infra-legacy/xenialOther threatsAffected
  • <2016.01+dfsg1-2ubuntu5+esm1
Fixed in
  • 2016.01+dfsg1-2ubuntu5+esm1
Ubuntu Pro 18.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=esm-infra/bionicOther threatsAffected
  • <2020.10+dfsg-1ubuntu0~18.04.3+esm1
Fixed in
  • 2020.10+dfsg-1ubuntu0~18.04.3+esm1
Ubuntu Pro 20.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=esm-infra/focalOther threatsAffected
  • <2021.01+dfsg-3ubuntu0~20.04.6+esm1
Fixed in
  • 2021.01+dfsg-3ubuntu0~20.04.6+esm1
Ubuntu 22.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=jammyOther threatsAffected
  • <2022.01+dfsg-2ubuntu2.8
Fixed in
  • 2022.01+dfsg-2ubuntu2.8
Ubuntu 22.04 LTSu-boot-nezhapkg:deb/ubuntu/u-boot-nezha?arch=source&distro=jammyOther threatsAffected
  • 2021.09+git20211008.62392d3-0ubuntu1 – 2022.04+git20220405.7446a472-0ubuntu0.4
5 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available for this vulnerability. Users should upgrade to U-Boot version 2026.10-rc3 or later where the issue is fixed. There are no vendor advisories indicating that no action is required or that the issue is already mitigated.

Description

U-Boot versions prior to 2026.10-rc3 with CONFIG_IP_DEFRAG enabled contain an out-of-bounds write vulnerability in the __net_defragment() function. This vulnerability allows remote attackers to send crafted IP fragments during netboot, potentially corrupting adjacent memory and causing the bootloader to crash. The vulnerability has a CVSS score of 8.2, indicating a medium severity level. A patch is available to address this issue.

References

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