# CVE-2026-74221 — u-boot

> As of 2026-09-30, CVE-2026-74221 is a HIGH-severity vulnerability in u-boot, CVSS v3.1 8.2. No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-74221 as of 2026-09-30; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-30

## What is CVE-2026-74221?

U-Boot before 2026.10-rc5 contains a buffer overflow in nfs_readlink_reply() function in net/nfs-common.c when processing NFS server responses. A malicious NFS server can send crafted READLINK replies with negative or oversized symlink length values to corrupt memory and crash the bootloader.

The record classifies CVE-2026-74221 under weakness class [CWE-195](https://cwe.mitre.org/data/definitions/195.html). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 6 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.2 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H`)
- **CVSS v4.0 base score:** 8.8 (`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 KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.1/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-29, last modified 2026-09-30

## Is CVE-2026-74221 being exploited?

It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **u-boot**: u-boot

## How to fix CVE-2026-74221

No vendor patch reference has been recorded for CVE-2026-74221 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-74221

No threat campaign in the Threadlinqs corpus currently references CVE-2026-74221, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org. Last verified by Threadlinqs on 2026-09-30.

**Vendor advisory and patch**

- [github.com — patch](https://github.com/u-boot/u-boot/commit/1c0aff3a5fbfeee7a8948f624e0b8554e6e0d8fd)

**Technical analysis**

- [github.com — technical description](https://github.com/u-boot/u-boot/blob/v2026.07/net/nfs-common.c#L643)

**Third-party advisory**

- [vulncheck.com — third party advisory](https://www.vulncheck.com/advisories/u-boot-before-2026.10-rc5-buffer-overflow-via-nfs-readlink)

**Issue tracking and product pages**

- [github.com — product](https://github.com/u-boot/u-boot)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-74221
Full detection coverage and IOCs for threats exploiting CVE-2026-74221 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp