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8.6
CVE-2026-71971: U-Boot can crash from crafted network packets
CVE-2026-71971 · published 1 month ago
Summary
U-Boot bootloaders that have the IP reassembly feature turned on may write outside memory when they receive a specially formed network packet during the boot process. This can corrupt memory and cause the bootloader to stop working. Update U-Boot to a version released after October 2026 or disable the IP fragmentation feature to protect the system.
What to do
- Update canonical u-boot to version 2016.01+dfsg1-2ubuntu5+esm1.
- Update canonical u-boot to version 2020.10+dfsg-1ubuntu0~18.04.3+esm1.
- Update canonical u-boot to version 2021.01+dfsg-3ubuntu0~20.04.6+esm1.
- Update canonical u-boot to version 2022.01+dfsg-2ubuntu2.8.
- Update canonical u-boot to version 2025.10-0ubuntu0.24.04.3.
- Update canonical u-boot to version 2025.10-0ubuntu5.
- Update canonical u-boot to version 2025.10-0ubuntu2.1.
- Update u-boot u-boot to version 2026.10-rc3 or later.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| – | u-boot | u-boot | < 2026.10-rc3 |
| Ubuntu:16.04:LTS | canonical | u-boot | All versions |
| Ubuntu:22.04:LTS | canonical | u-boot-nezha | All versions |
| Debian:12 | debian | u-boot | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | u-boot |
< 2016.01+dfsg1-2ubuntu5+esm1 Fix: upgrade to 2016.01+dfsg1-2ubuntu5+esm1
|
| Ubuntu:Pro:18.04:LTS | canonical | u-boot |
< 2020.10+dfsg-1ubuntu0~18.04.3+esm1 Fix: upgrade to 2020.10+dfsg-1ubuntu0~18.04.3+esm1
|
| Ubuntu:Pro:20.04:LTS | canonical | u-boot |
< 2021.01+dfsg-3ubuntu0~20.04.6+esm1 Fix: upgrade to 2021.01+dfsg-3ubuntu0~20.04.6+esm1
|
| Ubuntu:22.04:LTS | canonical | u-boot |
< 2022.01+dfsg-2ubuntu2.8 Fix: upgrade to 2022.01+dfsg-2ubuntu2.8
|
| Ubuntu:24.04:LTS | canonical | u-boot |
< 2025.10-0ubuntu0.24.04.3 Fix: upgrade to 2025.10-0ubuntu0.24.04.3
|
| Ubuntu:26.10 | canonical | u-boot |
< 2025.10-0ubuntu5 Fix: upgrade to 2025.10-0ubuntu5
|
| Ubuntu:26.04:LTS | canonical | u-boot |
< 2025.10-0ubuntu2.1 Fix: upgrade to 2025.10-0ubuntu2.1
|
Original advisory text
U-Boot before 2026.10-rc3 Out-of-Bounds Write in IP Fragment Reassembly
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.
References
- https://ubuntu.com/security/notices/USN-8884-1 Vendor Advisory
- https://github.com/u-boot/u-boot/commit/04ca915d5bf39dda5d1bce62d04d2b59d293c5b9 Patch
- https://github.com/u-boot/u-boot Product
- https://github.com/u-boot/u-boot/blob/v2026.07/net/net.c#L975 Third Party Advisory
- https://ubuntu.com/security/CVE-2026-71971 Third Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2026-71971 Third Party Advisory
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/71xxx/CVE-2026-71971... Vendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-71971 Vendor Advisory
- https://security-tracker.debian.org/tracker/CVE-2026-71971 Vendor Advisory
- https://www.vulncheck.com/advisories/u-boot-before-2026.10-rc3-out-of-bounds-wri... Vendor Advisory
Internet-facing
14 days
Internal
60 days
- Not known to be exploited
- Can be exploited automatically
- Gives an attacker partial control
Severity
8.6
High
Type
CWE-787Out-of-bounds Write
Timeline
Published29 Sep 2026
Updated4 Nov 2026
First seen29 Sep 2026
Sources
CVE-2026-71971 · OSV
CVE-2026-71971 · NVD
CVE-2026-71971 · MITRE
UBUNTU-CVE-2026-71971 · OSV
DEBIAN-CVE-2026-71971 · OSV
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