# CVE-2026-89953: mtd: mtdoops: free page bitmap when the backing MTD is removed

> A memory leak in the Linux kernel mtdoops driver allows local attackers to exhaust memory by repeatedly removing and re-adding MTD devices.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-101562, BELL-CVE-2026-89953, DEBIAN-CVE-2026-89953, GHSA-wvj7-v5wh-67w6, UBUNTU-CVE-2026-89953

## What is CVE-2026-89953?

CVE-2026-89953 is a memory corruption vulnerability in Linux, published on 16 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: mtdoops: free page bitmap when the backing MTD is removed

mtdoops_notify_add() allocates oops_page_used when the configured MTD
device is registered.  mtdoops_notify_remove() detaches from that device
but leaves the bitmap allocated.  If the same MTD device is later
registered again, the add path allocates a new bitmap and overwrites the
old pointer, leaking one vmalloc allocation per remove/add cycle.

This is only visible when the backing MTD device can disappear and be
registered again while mtdoops remains loaded, so the usual static MTD
case does not expose it.

Free the bitmap after unregistering the dumper and flushing the pending
workers, then clear the pointer and page count before a later attach can
allocate fresh state.  Clearing the pointer also keeps the module exit
path from freeing the same bitmap a second time after a remove event.

## Which versions are affected by CVE-2026-89953?


## How do I fix CVE-2026-89953?

Apply the vendor's patch.

## Is CVE-2026-89953 being exploited?

There is no known exploitation of CVE-2026-89953 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89953 and fix it if it is affected.

What it is: CVE-2026-89953 is a memory corruption vulnerability in Linux, published on 16 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-2026-89953 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-2026-89953/ (Markdown: https://insights.sbomify.com/CVE-2026-89953/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89953
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89953
- OSV: https://osv.dev/vulnerability/CVE-2026-89953

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89953/
Summaries are generated and may contain mistakes; the official description above is the record.