# CVE-2026-98017: net/sched: defer qdisc freeing after failed creation

> A use-after-free in the Linux kernel network scheduler allows attackers to cause denial of service or execute code via crafted RTM_NEWQDISC requests.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/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:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-104457, BELL-CVE-2026-98017, DEBIAN-CVE-2026-98017, GHSA-wjw6-9w8q-rvjv, UBUNTU-CVE-2026-98017

## What is CVE-2026-98017?

CVE-2026-98017 is a high-severity use after free vulnerability in Linux, published on 25 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:

net/sched: defer qdisc freeing after failed creation

An RTM_NEWQDISC request can make clsact bind a populated shared ingress
block during ->init(), publishing an embedded mini_Qdisc to lockless
readers.  If the same request has an invalid TCA_RATE, estimator setup
fails after ->init(); the unwind removes the pointer but synchronously
frees its containing qdisc while tc_run() may still hold it.

Retire failed qdiscs through the same RCU helper as normal destruction.
Inline the synchronous free into the callback now that no direct callers
remain.

## Which versions are affected by CVE-2026-98017?


## How do I fix CVE-2026-98017?

Apply the vendor's patch.

## Is CVE-2026-98017 being exploited?

There is no known exploitation of CVE-2026-98017 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98017 and fix it if it is affected.

What it is: CVE-2026-98017 is a high-severity use after free vulnerability in Linux, published on 25 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-2026-98017 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-2026-98017/ (Markdown: https://insights.sbomify.com/CVE-2026-98017/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98017
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98017
- OSV: https://osv.dev/vulnerability/CVE-2026-98017

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98017/
Summaries are generated and may contain mistakes; the official description above is the record.