# CVE-2026-98921: ovl: fix UAF in ovl_do_mkdir() debug print


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 23 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-98921, GHSA-5m82-wc7w-682w, UBUNTU-CVE-2026-98921

## What is CVE-2026-98921?

CVE-2026-98921 is a vulnerability in Linux, published on 23 Oct 2026. 

### Official description

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

ovl: fix UAF in ovl_do_mkdir() debug print

ovl_do_mkdir() prints the input dentry with %pd after vfs_mkdir().
Since commit fe497f0759e0 ("VFS: change vfs_mkdir() to unlock on
failure."), vfs_mkdir() calls end_creating() on the input dentry on
failure and may replace it on success, so the post-call %pd can
use-after-free the dentry when CONFIG_OVERLAY_FS_DEBUG is enabled.

Print the dentry before the call and only the result afterward.

## Which versions are affected by CVE-2026-98921?


## How do I fix CVE-2026-98921?

Upgrade to a fixed version.

## Is CVE-2026-98921 being exploited?

There is no known exploitation of CVE-2026-98921 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98921 and fix it if it is affected.

What it is: CVE-2026-98921 is a vulnerability in Linux, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-98921 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-2026-98921/ (Markdown: https://insights.sbomify.com/CVE-2026-98921/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98921
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98921
- OSV: https://osv.dev/vulnerability/CVE-2026-98921

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98921/
Summaries are generated and may contain mistakes; the official description above is the record.