# CVE-2026-74466: s390/zcrypt: Close speculative mem read possibility

> A local attacker with low privileges can exploit speculative execution in the s390/zcrypt driver to read sensitive memory, requiring specific device node access.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-74466, DEBIAN-CVE-2026-74466, GHSA-4w55-4rvm-3v48, UBUNTU-CVE-2026-74466

## What is CVE-2026-74466?

CVE-2026-74466 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

s390/zcrypt: Close speculative mem read possibility

The domain value is extracted from a given CCA or EP11 ioctl struct
when a CPRB is about to be sent. Thus this is a user controlled value.
Under some special conditions (custom device node used, administrative
load) this value is used as an array index after bounds checking, but
without speculation barrier.

Add the missing array_index_nospec() call to prevent speculative
execution where this domain value is used.

## Which versions are affected by CVE-2026-74466?


## How do I fix CVE-2026-74466?

Apply the vendor's patch.

## Is CVE-2026-74466 being exploited?

There is no known exploitation of CVE-2026-74466 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74466 and fix it if it is affected.

What it is: CVE-2026-74466 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74466 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-2026-74466/ (Markdown: https://insights.sbomify.com/CVE-2026-74466/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74466
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74466
- OSV: https://osv.dev/vulnerability/CVE-2026-74466

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74466/
Summaries are generated and may contain mistakes; the official description above is the record.