---
title: "CVE-2026-74221: U-Boot - Buffer Overflow"
description: "U-Boot before 2026.10-rc5 contains a buffer overflow caused by improper handling of crafted READLINK replies with negative or oversized symlink length values in nfs_readlink_reply() function, letting malicious NFS servers corrupt memory and crash the bootloader, exploit requires interaction with a malicious NFS server."
url: https://panop.io/threat-heartbeat/CVE-2026-74221/
---

# CVE-2026-74221 U-Boot - Buffer Overflow

U-Boot before 2026.10-rc5 contains a buffer overflow caused by improper handling of crafted READLINK replies with negative or oversized symlink length values in nfs\_readlink\_reply() function, letting malicious NFS servers corrupt memory and crash the bootloader, exploit requires interaction with a malicious NFS server.

CVSS base score 8.2 /10

High

CISA KEV

Not listed

Public exploit

None known

EPSS

0.34% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-74221)

## Details

Type

Buffer Overflow

Impact

Denial Of Service

CVSS vector

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

Published

29 September 2026

Updated

15 October 2026

Weakness

[CWE-195](https://cwe.mitre.org/data/definitions/195.html)

## Vendor fix

Update to version 2026.10-rc5 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-74221](https://nvd.nist.gov/vuln/detail/CVE-2026-74221)
- [https://www.vulncheck.com/advisories/u-boot-before-2026.10-rc5-buffer-overflow-via-nfs-readlink](https://www.vulncheck.com/advisories/u-boot-before-2026.10-rc5-buffer-overflow-via-nfs-readlink)
- [https://github.com/u-boot/u-boot](https://github.com/u-boot/u-boot)
- [https://github.com/u-boot/u-boot/blob/v2026.07/net/nfs-common.c#L643](https://github.com/u-boot/u-boot/blob/v2026.07/net/nfs-common.c#L643)
- [https://github.com/u-boot/u-boot/commit/1c0aff3a5fbfeee7a8948f624e0b8554e6e0d8fd](https://github.com/u-boot/u-boot/commit/1c0aff3a5fbfeee7a8948f624e0b8554e6e0d8fd)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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