# CVE-2023-53826: ubi: Fix UAF wear-leveling entry in eraseblk_count_seq_show()

> A use-after-free vulnerability in the Linux kernel UBI subsystem allows local attackers to potentially execute code or escalate privileges via race conditions in wear-leveling entry handling.

- **Severity:** Not scored
- **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:** 9 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-53826, DEBIAN-CVE-2023-53826, GHSA-39w7-pr2v-3x67, UBUNTU-CVE-2023-53826

## What is CVE-2023-53826?

CVE-2023-53826 is an use after free vulnerability in Linux, published on 9 Dec 2025. 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:

ubi: Fix UAF wear-leveling entry in eraseblk_count_seq_show()

Wear-leveling entry could be freed in error path, which may be accessed
again in eraseblk_count_seq_show(), for example:

__erase_worker                eraseblk_count_seq_show
                                wl = ubi->lookuptbl[*block_number]
				if (wl)
  wl_entry_destroy
    ubi->lookuptbl[e->pnum] = NULL
    kmem_cache_free(ubi_wl_entry_slab, e)
		                   erase_count = wl->ec  // UAF!

Wear-leveling entry updating/accessing in ubi->lookuptbl should be
protected by ubi->wl_lock, fix it by adding ubi->wl_lock to serialize
wl entry accessing between wl_entry_destroy() and
eraseblk_count_seq_show().

Fetch a reproducer in [Link].

## Which versions are affected by CVE-2023-53826?


## How do I fix CVE-2023-53826?

Apply the vendor's patch.

## Is CVE-2023-53826 being exploited?

There is no known exploitation of CVE-2023-53826 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-53826 and fix it if it is affected.

What it is: CVE-2023-53826 is an use after free vulnerability in Linux, published on 9 Dec 2025. 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-2023-53826 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-2023-53826/ (Markdown: https://insights.sbomify.com/CVE-2023-53826/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53826
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53826
- OSV: https://osv.dev/vulnerability/CVE-2023-53826

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53826/
Summaries are generated and may contain mistakes; the official description above is the record.