# CVE-2026-90182: blk-iocost: clear delay state when freeing policy data

> A local attacker can cause persistent I/O throttling and performance degradation in Linux by triggering a state management error in the blk-iocost scheduler.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-101951, BELL-CVE-2026-90182, DEBIAN-CVE-2026-90182, GHSA-3p27-2gjm-jxc2, UBUNTU-CVE-2026-90182

## What is CVE-2026-90182?

CVE-2026-90182 is a denial of service 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:

blk-iocost: clear delay state when freeing policy data

iocg_kick_delay() turns sufficiently large debt into an explicit
block-cgroup delay with blkcg_set_delay(), setting blkg->use_delay to
-1 and incrementing blkcg->congestion_count.  Clearing it again depends
on iocg_kick_delay() running from the period timer, the waitq timer or
the issue path.

ioc_pd_free() removes the iocg from active_iocgs and cancels its waitq
timer, and no further bios can arrive, so once it has run nothing is
left which can reduce the debt and clear the delay.  The blkcg stays
marked congested for the rest of its life.

blk_cgroup_congested() then returns true for every task in that cgroup
and its descendants: page_cache_sync_ra() cuts readahead to a single
page, page_cache_async_ra() skips it altogether, and
__folio_throttle_swaprate() takes swap_avail_lock and schedules a
throttle on anonymous folio allocation.

Clear it explicitly, after the list removal and the synchronous
hrtimer_cancel() so that neither timer processing nor an I/O path can
re-arm it.  The free callback can also see policy data which was never
attached to a blkg, hence the pd->blkg check.

## Which versions are affected by CVE-2026-90182?


## How do I fix CVE-2026-90182?

Apply the vendor's patch.

## Is CVE-2026-90182 being exploited?

There is no known exploitation of CVE-2026-90182 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90182 and fix it if it is affected.

What it is: CVE-2026-90182 is a denial of service 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-2026-90182 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-2026-90182/ (Markdown: https://insights.sbomify.com/CVE-2026-90182/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90182
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90182
- OSV: https://osv.dev/vulnerability/CVE-2026-90182

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90182/
Summaries are generated and may contain mistakes; the official description above is the record.