# CVE-2026-99096: io_uring/register: don't exempt disabled rings from task restrictions


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 26 Oct 2026
- **Updated:** 26 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-99096, GHSA-4xv2-crf6-2mgc, UBUNTU-CVE-2026-99096

## What is CVE-2026-99096?

CVE-2026-99096 is a vulnerability in Linux, published on 26 Oct 2026. 

### Official description

In the Linux kernel, the following vulnerability has been resolved:

io_uring/register: don't exempt disabled rings from task restrictions

A ring created with IORING_SETUP_R_DISABLED is exempt from its register
restrictions until it is enabled. This lets the creator register the
restrictions and then enable the ring with IORING_REGISTER_ENABLE_RINGS,
whether or not that opcode is in the allowed set.

Since commit ed82f35b926b ("io_uring: allow registration of per-task
restrictions"), a ring also inherits restrictions from the task that
creates it, and the same exemption applies to those. A task whose
register opcodes are restricted can therefore create a disabled ring,
issue any register opcode on it, and then enable it.

Mark rings whose restrictions were inherited from the task, and keep
checking register opcodes for them while the ring is disabled. Enabling
such a ring now requires IORING_REGISTER_ENABLE_RINGS to be in the
task's allowed set. Per-ring restrictions registered on a disabled ring
work as before.

[axboe: amend with inheritance flag fixup]

## Which versions are affected by CVE-2026-99096?


## How do I fix CVE-2026-99096?

Upgrade to a fixed version.

## Is CVE-2026-99096 being exploited?

There is no known exploitation of CVE-2026-99096 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99096 and fix it if it is affected.

What it is: CVE-2026-99096 is a vulnerability in Linux, published on 26 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99096 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-2026-99096/ (Markdown: https://insights.sbomify.com/CVE-2026-99096/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99096
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99096
- OSV: https://osv.dev/vulnerability/CVE-2026-99096

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99096/
Summaries are generated and may contain mistakes; the official description above is the record.