# CVE-2025-68248: vmw_balloon: indicate success when effectively deflating during migration

> A logic error in the Linux kernel's vmw_balloon driver causes a kernel warning and potential instability during page migration, leading to denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-68248, GHSA-98x7-gjfm-r896, UBUNTU-CVE-2025-68248

## What is CVE-2025-68248?

CVE-2025-68248 is a denial of service vulnerability in Linux, published on 16 Dec 2025. 

### Official description

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

vmw_balloon: indicate success when effectively deflating during migration

When migrating a balloon page, we first deflate the old page to then
inflate the new page.

However, if inflating the new page succeeded, we effectively deflated the
old page, reducing the balloon size.

In that case, the migration actually worked: similar to migrating+
immediately deflating the new page.  The old page will be freed back to
the buddy.

Right now, the core will leave the page be marked as isolated (as we
returned an error).  When later trying to putback that page, we will run
into the WARN_ON_ONCE() in balloon_page_putback().

That handling was changed in commit 3544c4faccb8 ("mm/balloon_compaction:
stop using __ClearPageMovable()"); before that change, we would have
tolerated that way of handling it.

To fix it, let's just return 0 in that case, making the core effectively
just clear the "isolated" flag + freeing it back to the buddy as if the
migration succeeded.  Note that the new page will also get freed when the
core puts the last reference.

Note that this also makes it all be more consistent: we will no longer
unisolate the page in the balloon driver while keeping it marked as being
isolated in migration core.

This was found by code inspection.

## Which versions are affected by CVE-2025-68248?


## How do I fix CVE-2025-68248?

Apply the vendor's patch.

## Is CVE-2025-68248 being exploited?

There is no known exploitation of CVE-2025-68248 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68248 and fix it if it is affected.

What it is: CVE-2025-68248 is a denial of service vulnerability in Linux, published on 16 Dec 2025. 
Exploitation: There is no known exploitation of CVE-2025-68248 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-2025-68248/ (Markdown: https://insights.sbomify.com/CVE-2025-68248/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68248
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68248
- OSV: https://osv.dev/vulnerability/CVE-2025-68248

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68248/
Summaries are generated and may contain mistakes; the official description above is the record.