CVE-2026-29009: Denx U-boot buffer overflow (CVSS 8.2)

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.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityNone

IntegrityLow

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected products

Denx U-boot< 2026.04 · 2026.04

Remediation

Fixed in

Denx U-boot≥ 2026.04

References

https://git.u-boot-project.org/u-boot/u-boot/-/commit/d6694018eaddefac6aae974f9cec72fd6e58f1bc
https://git.u-boot-project.org/u-boot/u-boot/-/releases/v2026.07-rc2
https://lists.denx.de/pipermail/u-boot/2026-May/617853.htmlMailing ListThird Party Advisory
https://u-boot.org/Product
https://www.vulncheck.com/advisories/u-boot-rc3-buffer-overflow-in-nfs-readlink-reply-via-nfs-readlinkExploitThird Party Advisory
https://y637f9qq2x.com/posts/u-boot-tcp-nfs-vulns/ExploitThird Party Advisory

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-29009 being actively exploited?

CVE-2026-29009 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.74%.

How severe is CVE-2026-29009?

CVE-2026-29009 has a CVSS 3.1 base score of 8.2, rated high. EPSS estimates a 0.74% probability of exploitation.

Which products are affected by CVE-2026-29009?

Affected products include Denx U-boot.

How do I fix CVE-2026-29009?

Upgrade affected software to a fixed version, for example Denx U-boot 2026.04 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-29009 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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