# CVE-2026-93049: mtd: mtdswap: Avoid freeing registered blktrans device twice

> A double-free vulnerability in the Linux kernel's mtdswap driver allows local attackers to cause a denial of service or potentially execute arbitrary code.

- **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:** 19 Oct 2026
- **Also known as:** AZL-102629, BELL-CVE-2026-93049, DEBIAN-CVE-2026-93049, GHSA-vm56-mgvf-744c, UBUNTU-CVE-2026-93049

## What is CVE-2026-93049?

CVE-2026-93049 is an use after free 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:

mtd: mtdswap: Avoid freeing registered blktrans device twice

In mtdswap_add_mtd(), debugfs setup failure after successful blktrans
registration can free mbd_dev twice.

add_mtd_blktrans_dev() initializes the blktrans device reference and
publishes the disk. Once that succeeds, del_mtd_blktrans_dev() tears the
disk down and drops the blktrans reference; when that reference reaches
zero, blktrans_dev_release() frees the mtd_blktrans_dev.

The debugfs failure path called del_mtd_blktrans_dev(mbd_dev), then fell
through the common cleanup label and called kfree(mbd_dev) again. Clear
the local pointer after deregistration so the common cleanup can still
release the mtdswap state without freeing the blktrans object twice.

This issue was found by a static analysis checker and confirmed by
manual source review.

## Which versions are affected by CVE-2026-93049?


## How do I fix CVE-2026-93049?

Apply the vendor's patch.

## Is CVE-2026-93049 being exploited?

There is no known exploitation of CVE-2026-93049 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93049 and fix it if it is affected.

What it is: CVE-2026-93049 is an use after free 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-2026-93049 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-2026-93049/ (Markdown: https://insights.sbomify.com/CVE-2026-93049/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93049
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93049
- OSV: https://osv.dev/vulnerability/CVE-2026-93049

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93049/
Summaries are generated and may contain mistakes; the official description above is the record.