Vulnerability · Published Sep 29, 2026 · Assigned by VulnCheck
CVE-2026-74220U-Boot before 2026.10-rc5 Buffer Overflow via NFS READ Reply
High 8.2
In plain English
A high-severity security flaw in u-boot from u-boot. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
U-Boot before 2026.10-rc5 contains a buffer overflow in nfs_read_reply() function in net/nfs-common.c that allows attackers to corrupt memory by supplying crafted NFS READ reply lengths. A malicious NFS server can exploit signed integer handling to bypass length validation and write far past the destination buffer, crashing the bootloader or corrupting memory.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | u-boot | no fix listed | DEBIAN-CVE-2026-74220 |
| Debian:13 | u-boot | no fix listed | DEBIAN-CVE-2026-74220 |
| Debian:14 | u-boot | no fix listed | DEBIAN-CVE-2026-74220 |
| Ubuntu:22.04:LTS | u-boot | 2022.01+dfsg-2ubuntu2.9 | USN-8930-1 |
| Ubuntu:22.04:LTS | u-boot | 2022.01+dfsg-2ubuntu2.9 | UBUNTU-CVE-2026-74220 |
| Ubuntu:24.04:LTS | u-boot | 2025.10-0ubuntu0.24.04.4 | UBUNTU-CVE-2026-74220 |
| Ubuntu:24.04:LTS | u-boot | 2025.10-0ubuntu0.24.04.4 | USN-8930-1 |
| Ubuntu:26.04:LTS | u-boot | 2025.10-0ubuntu2.2 | UBUNTU-CVE-2026-74220 |
| Ubuntu:26.04:LTS | u-boot | 2025.10-0ubuntu2.2 | USN-8930-1 |
| Ubuntu:26.10 | u-boot | 2025.10-0ubuntu6 | UBUNTU-CVE-2026-74220 |
| Ubuntu:26.10 | u-boot | 2025.10-0ubuntu6 | USN-8930-2 |
| Ubuntu:22.04:LTS | u-boot-nezha | no fix listed | UBUNTU-CVE-2026-74220 |
| Ubuntu:24.04:LTS | u-boot-nezha | no fix listed | UBUNTU-CVE-2026-74220 |
Affected products (as reported)
Weakness: CWE-195 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
References
- https://github.com/u-boot/u-boot/commit/0bbf09859658b8cc9ac13be41af23b516b8ef69a patch
- https://github.com/u-boot/u-boot/blob/v2026.07/net/nfs-common.c#L695 technical-description
- https://github.com/u-boot/u-boot product
- VulnCheck Advisory: U-Boot before 2026.10-rc5 Buffer Overflow via NFS READ Reply third-party-advisory