# CVE-2026-90185: null_blk: serialize configfs attribute stores with the lock

> A race condition in the Linux kernel null_blk driver allows local attackers to cause out-of-bounds memory access and system crashes via concurrent configfs writes.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102582, BELL-CVE-2026-90185, DEBIAN-CVE-2026-90185, GHSA-66h5-crgq-784h, UBUNTU-CVE-2026-90185

## What is CVE-2026-90185?

CVE-2026-90185 is a vulnerability in Linux, published on 17 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:

null_blk: serialize configfs attribute stores with the lock

The NULLB_DEVICE_ATTR _store takes no lock: apply_fn attributes
(submit_queues, poll_queues) get dev->NAME written again after apply_fn
returns, outside its lock; APPLY=NULL attributes are entirely lockless.
configfs only serializes stores per-open-file, so concurrent stores on
separate fds race.

For apply_fn attributes, once one store's apply_fn has reconfigured the
hardware, a second (losing) store can still overwrite dev->NAME
afterwards. This leaves dev->submit_queues out of sync with the live
queue count, which is later caught by the WARN_ON_ONCE() in
null_map_queues().

For !apply_fn attributes, power_store()'s null_add_dev() validates and
builds the device under "lock" but only sets CONFIGURED afterwards. A store
slipping in during this window can change a field mid-setup -- for example,
zone_nr_conv can be pushed above nr_zones after it has already been
clamped, leading to an out-of-bounds dev->zones[] access.

Take "lock" in the macro around the apply_fn call, the CONFIGURED test and
the field write, and move it out of nullb_apply_submit_queues()/
nullb_apply_poll_queues() so both paths are covered once. This serializes
stores with power_store's setup and with each other.

## Which versions are affected by CVE-2026-90185?


## How do I fix CVE-2026-90185?

Apply the vendor's patch.

## Is CVE-2026-90185 being exploited?

There is no known exploitation of CVE-2026-90185 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90185 and fix it if it is affected.

What it is: CVE-2026-90185 is a vulnerability in Linux, published on 17 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-2026-90185 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-2026-90185/ (Markdown: https://insights.sbomify.com/CVE-2026-90185/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90185
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90185
- OSV: https://osv.dev/vulnerability/CVE-2026-90185

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90185/
Summaries are generated and may contain mistakes; the official description above is the record.