# CVE-2026-74402: crypto: atmel-sha204a - fix blocking and non-blocking rng logic

> A flaw in the Atmel SHA204A kernel driver caused weak entropy generation, potentially compromising cryptographic security for users relying on this hardware random number generator.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-74402, DEBIAN-CVE-2026-74402, GHSA-5f8p-9776-4575, UBUNTU-CVE-2026-74402

## What is CVE-2026-74402?

CVE-2026-74402 is a vulnerability in Linux, published on 15 Aug 2026. 

### Official description

In the Linux kernel, the following vulnerability has been resolved:

crypto: atmel-sha204a - fix blocking and non-blocking rng logic

The blocking and non-blocking paths were failing to provide valid entropy
due to improper buffer management. Reading the buffer starting from byte 1,
only fetch the 32 bytes of random data from the return message.

Tested on an Atmel SHA204A device.

Before (here for blocking), tests showed repeatedly reading reduced bytes.
$ head -c 32 /dev/hwrng | hexdump -C
00000000  02 28 85 b3 47 40 f2 ee  00 00 00 00 00 00 00 00  |.(..G@..........|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020

After, the result will be similar to the following:
$ head -c 32 /dev/hwrng | hexdump -C
00000000  5a fc 3f 13 14 68 fe 06  68 0a bd 04 83 6e 09 69  |Z.?..h..h....n.i|
00000010  75 ff cf 87 10 84 3b c9  c1 df ae eb 45 53 4c c3  |u.....;.....ESL.|
00000020

## Which versions are affected by CVE-2026-74402?


## How do I fix CVE-2026-74402?

Apply the vendor's patch.

## Is CVE-2026-74402 being exploited?

There is no known exploitation of CVE-2026-74402 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74402 and fix it if it is affected.

What it is: CVE-2026-74402 is a vulnerability in Linux, published on 15 Aug 2026. 
Exploitation: There is no known exploitation of CVE-2026-74402 in the wild and no public exploit code.

Affected product: Linux. 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-2026-74402/ (Markdown: https://insights.sbomify.com/CVE-2026-74402/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74402
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74402
- OSV: https://osv.dev/vulnerability/CVE-2026-74402

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74402/
Summaries are generated and may contain mistakes; the official description above is the record.