# CVE-2026-89456: s390/dasd: Propagate partial completion length across ERP recovery

> A Linux kernel bug in s390 DASD drivers causes partial read failures to return zeroed data instead of requeuing, leading to silent data corruption or information disclosure.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100901, BELL-CVE-2026-89456, DEBIAN-CVE-2026-89456, GHSA-54rx-hjqg-c852, UBUNTU-CVE-2026-89456

## What is CVE-2026-89456?

CVE-2026-89456 is a high-severity vulnerability in Linux, published on 11 Sep 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/dasd: Propagate partial completion length across ERP recovery

dasd_default_erp_postaction() copies the timing and device state from
the finished ERP request back to the original request but drops
proc_bytes. A request that was partially completed, an ESE read of a
not-yet-allocated track returns fewer bytes than requested, and then
recovered through the ERP chain loses its partial-completion length.
__dasd_cleanup_cqr() then sees proc_bytes == 0 and completes the whole
request instead of requeueing the remainder, silently returning zeroed
data for the part that was never read.

Carry proc_bytes over to the original request like the other
per-request state.

## Which versions are affected by CVE-2026-89456?


## How do I fix CVE-2026-89456?

Apply the vendor's patch.

## Is CVE-2026-89456 being exploited?

There is no known exploitation of CVE-2026-89456 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89456 and fix it if it is affected.

What it is: CVE-2026-89456 is a high-severity vulnerability in Linux, published on 11 Sep 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-2026-89456 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-2026-89456/ (Markdown: https://insights.sbomify.com/CVE-2026-89456/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89456
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89456
- OSV: https://osv.dev/vulnerability/CVE-2026-89456

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89456/
Summaries are generated and may contain mistakes; the official description above is the record.