Buffer overflow in Denx U-Boot
CVE-2026-29009
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H.
EPSS exploit prediction
EPSS: 0.007 (53.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 53.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000
Affected products
- Denx U-Boot — versions 2026.04
- U-Boot — versions 0
Weakness classification (CWE)
References
- lists.denx.de/pipermail/u-boot/2026-May/617853.html (issue-tracking, Mailing List, Third Party Advisory)
- u-boot.org/ (Product, product)
- www.vulncheck.com/advisories/u-boot-rc3-buffer-overflow-in-nfs-readlink-reply-v… (Exploit, Third Party Advisory, third-party-advisory)
- y637f9qq2x.com/posts/u-boot-tcp-nfs-vulns/ (Exploit, technical-description, Third Party Advisory, exploit)
- git.u-boot-project.org/u-boot/u-boot/-/releases/v2026.07-rc2 (release-notes)
- git.u-boot-project.org/u-boot/u-boot/-/commit/d6694018eaddefac6aae974f9cec72fd6… (patch)
Frequently asked questions
- What is CVE-2026-29009?
- CVE-2026-29009 is a high-severity vulnerability in Denx U-Boot, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 8.2/10. Published 2026-07-08.
- How severe is CVE-2026-29009?
- High severity. CVSS v3 base score is 8.2 out of 10.