# CVE-2026-42493: x86 shadow paging is deprecated

> Xen deprecates x86 shadow paging due to excessive resource consumption risks, requiring users to switch to HAP or shim modes to avoid potential denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Jul 2026
- **Updated:** 28 Jul 2026
- **Also known as:** ALPINE-CVE-2026-42493, DEBIAN-CVE-2026-42493, GHSA-7jxp-562x-944j, UBUNTU-CVE-2026-42493

## What is CVE-2026-42493?

CVE-2026-42493 is a high-severity denial of service vulnerability in Xen, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Addressing certain issues, in particular related to operations which may
take excessively long and therefore would need preemption, has turned out
overly costly.  Since alternatives (HVM/PVH: HAP, PV: shim) are commonly
available, the decision was to deprecate the functionality, while still
retaining it for people to use at their own (security) risk.  Memory-wise
small enough guests may still be okay to run.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-42493?


## How do I fix CVE-2026-42493?

Change a configuration setting.

## Is CVE-2026-42493 being exploited?

There is no known exploitation of CVE-2026-42493 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42493 and fix it if it is affected.

What it is: CVE-2026-42493 is a high-severity denial of service vulnerability in Xen, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-42493 in the wild and no public exploit code.

Affected product: Xen. 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-2026-42493/ (Markdown: https://insights.sbomify.com/CVE-2026-42493/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42493
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42493
- OSV: https://osv.dev/vulnerability/CVE-2026-42493

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42493/
Summaries are generated and may contain mistakes; the official description above is the record.