# CVE-2023-53996: x86/sev: Make enc_dec_hypercall() accept a size instead of npages

> Incorrect page rounding in SEV hypercalls causes data corruption during live migration by marking non-aligned pages as decrypted.

- **Severity:** Critical 9.3 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **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:** 24 Dec 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2023-53996, DEBIAN-CVE-2023-53996, GHSA-5899-4q59-gc9f, UBUNTU-CVE-2023-53996

## What is CVE-2023-53996?

CVE-2023-53996 is a critical vulnerability in Linux, published on 24 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:

x86/sev: Make enc_dec_hypercall() accept a size instead of npages

enc_dec_hypercall() accepted a page count instead of a size, which
forced its callers to round up. As a result, non-page aligned
vaddrs caused pages to be spuriously marked as decrypted via the
encryption status hypercall, which in turn caused consistent
corruption of pages during live migration. Live migration requires
accurate encryption status information to avoid migrating pages
from the wrong perspective.

## Which versions are affected by CVE-2023-53996?


## How do I fix CVE-2023-53996?

Apply the vendor's patch.

## Is CVE-2023-53996 being exploited?

There is no known exploitation of CVE-2023-53996 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-53996 and fix it if it is affected.

What it is: CVE-2023-53996 is a critical vulnerability in Linux, published on 24 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-2023-53996 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-2023-53996/ (Markdown: https://insights.sbomify.com/CVE-2023-53996/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53996
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53996
- OSV: https://osv.dev/vulnerability/CVE-2023-53996

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53996/
Summaries are generated and may contain mistakes; the official description above is the record.