# CVE-2026-74221: U-Boot before 2026.10-rc5 Buffer Overflow via NFS READLINK

> A malicious NFS server can crash the U-Boot bootloader via a buffer overflow in the READLINK reply handler.

- **Severity:** High 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Sep 2026
- **Updated:** 30 Sep 2026
- **Also known as:** AZL-105702, DEBIAN-CVE-2026-74221, GHSA-r9ch-9wx4-f978, UBUNTU-CVE-2026-74221

## What is CVE-2026-74221?

CVE-2026-74221 is a high-severity memory corruption vulnerability in u-boot, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-195 (Signed to Unsigned Conversion Error)

## Which versions are affected by CVE-2026-74221?


## How do I fix CVE-2026-74221?

Upgrade to a fixed version.

## Is CVE-2026-74221 being exploited?

There is no known exploitation of CVE-2026-74221 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74221 and fix it if it is affected.

What it is: CVE-2026-74221 is a high-severity memory corruption vulnerability in u-boot, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74221 in the wild and no public exploit code.

Affected product: u-boot. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-74221/ (Markdown: https://insights.sbomify.com/CVE-2026-74221/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74221
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74221
- OSV: https://osv.dev/vulnerability/CVE-2026-74221

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74221/
Summaries are generated and may contain mistakes; the official description above is the record.