# CVE-2026-53124: ublk: reset per-IO canceled flag on each fetch

> A flaw in the Linux kernel ublk driver can cause a denial of service if the ublk server crashes during device recovery, leaving IOs stuck.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 24 Jun 2026
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2026-53124, DEBIAN-CVE-2026-53124, GHSA-xq85-jg4p-xf7w, UBUNTU-CVE-2026-53124

## What is CVE-2026-53124?

CVE-2026-53124 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jun 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:

ublk: reset per-IO canceled flag on each fetch

If a ublk server starts recovering devices but dies before issuing fetch
commands for all IOs, cancellation of the fetch commands that were
successfully issued may never complete. This is because the per-IO
canceled flag can remain set even after the fetch for that IO has been
submitted - the per-IO canceled flags for all IOs in a queue are reset
together only once all IOs for that queue have been fetched. So if a
nonempty proper subset of the IOs for a queue are fetched when the ublk
server dies, the IOs in that subset will never successfully be canceled,
as their canceled flags remain set, and this prevents ublk_cancel_cmd
from actually calling io_uring_cmd_done on the commands, despite the
fact that they are outstanding.

Fix this by resetting the per-IO cancel flags immediately when each IO
is fetched instead of waiting for all IOs for the queue (which may never
happen).

## Which versions are affected by CVE-2026-53124?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53124?

Apply the vendor's patch.

## Is CVE-2026-53124 being exploited?

There is no known exploitation of CVE-2026-53124 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53124 and fix it if it is affected.

What it is: CVE-2026-53124 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jun 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-2026-53124 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-53124/ (Markdown: https://insights.sbomify.com/CVE-2026-53124/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53124
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53124
- OSV: https://osv.dev/vulnerability/CVE-2026-53124

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53124/
Summaries are generated and may contain mistakes; the official description above is the record.