Description
U-Boot before 2026.07-rc2 contains a buffer overflow vulnerability in nfs_readlink_reply() (net/nfs-common.c) when CONFIG_CMD_NFS is enabled, allowing a malicious or compromised NFS server to overflow the 2048-byte nfs_path_buff buffer by returning multiple relative symlink targets that are appended without cumulative length validation. Attackers can send two or more READLINK responses containing relative symlink targets of approximately 1100 bytes each to corrupt adjacent BSS variables including nfs_server_ip, nfs_server_mount_port, nfs_server_port, nfs_our_port, nfs_state, and rpc_id, potentially achieving memory corruption and control over the NFS client state machine.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| u-boot | u-boot | < 2026.07-rc2 | 2026.07-rc2 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | u-boot | No fix yet | — |
| Debian 13 | u-boot | No fix yet | — |
| Debian 12 | u-boot | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | u-boot | No fix yet | — |
| Ubuntu 26.04 LTS | u-boot | No fix yet | — |
| Ubuntu 25.10 | u-boot | No fix yet | — |
| Ubuntu 24.04 LTS | u-boot +1 | No fix yet | — |
| Ubuntu 22.04 LTS | u-boot +1 | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | u-boot | No fix yet | — |
| Ubuntu Pro 18.04 LTS | u-boot | No fix yet | — |
| Ubuntu Pro 16.04 LTS | u-boot | No fix yet | — |
Advisories 1
- WID-SEC-2026-2306 DENX U-Boot: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jul 13, 2026
References
- Researcher Blog technical-description exploit
- Mailing List Outreach issue-tracking
- Release Notes release-notes
- Patch Commit patch
- Project Webpage
- https://www.vulncheck.com/advisories/u-boot-rc3-buffer-overflow-in-nfs-readlink-reply-via-nfs-readlink third-party-advisory