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
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 29 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
GitHubu-boot/u-bootpkg:github/u-boot/u-bootOther threats | Affected
| Fixed in
|
Ubuntu Pro 16.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=esm-infra-legacy/xenialOther threats | Affected
| Fixed in
|
Ubuntu Pro 18.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=esm-infra/bionicOther threats | Affected
| Fixed in
|
Ubuntu Pro 20.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=esm-infra/focalOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTSu-bootpkg:deb/ubuntu/u-boot?arch=source&distro=jammyOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTSu-boot-nezhapkg:deb/ubuntu/u-boot-nezha?arch=source&distro=jammyOther threats | Affected
| 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
- nvd.nist.gov/vuln/detail/CVE-2026-71971 (opens in a new tab)
- github.com/u-boot/u-boot/commit/04ca915d5bf39dda5d1bce62d04d2b59d293c5b9 (opens in a new tab)
- github.com/u-boot/u-boot (opens in a new tab)
- github.com/u-boot/u-boot/blob/v2026.07/net/net.c (opens in a new tab)
- vulncheck.com/advisories/u-boot-before-2026.10-rc3-out-of-bounds-write-in-ip-fragment-reassembly (opens in a new tab)
- ubuntu.com/security/CVE-2026-71971 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-71971 (opens in a new tab)
- ubuntu.com/security/notices/USN-8884-1 (opens in a new tab)