# CVE-2026-23554: Use after free of paging structures in EPT

> A use-after-free in Xen's EPT paging allows attackers to access unintended memory regions, potentially leading to data exposure or privilege escalation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **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:** 23 Mar 2026
- **Updated:** 23 Mar 2026
- **Also known as:** ALPINE-CVE-2026-23554, DEBIAN-CVE-2026-23554, GHSA-h6vw-38xq-3xwx, MGASA-2026-0068, SUSE-SU-2026:1092-1, UBUNTU-CVE-2026-23554

## What is CVE-2026-23554?

CVE-2026-23554 is a high-severity use after free vulnerability in Xen Xen, published on 23 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The Intel EPT paging code uses an optimization to defer flushing of any cached
EPT state until the p2m lock is dropped, so that multiple modifications done
under the same locked region only issue a single flush.

Freeing of paging structures however is not deferred until the flushing is
done, and can result in freed pages transiently being present in cached state.
Such stale entries can point to memory ranges not owned by the guest, thus
allowing access to unintended memory regions.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2026-23554?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `xen` | SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | All versions | 4.17.6_06-150500.3.62.2 |
| `xen` | SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | All versions | 4.17.6_06-150500.3.62.2 |
| `xen` | SUSE:Linux Enterprise Micro 5.5 | All versions | 4.17.6_06-150500.3.62.2 |
| `xen` | SUSE:Linux Enterprise Server 15 SP5-LTSS | All versions | 4.17.6_06-150500.3.62.2 |
| `xen` | SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | All versions | 4.17.6_06-150500.3.62.2 |

Products: Xen Xen.

## How do I fix CVE-2026-23554?

Apply the vendor's patch.

## Is CVE-2026-23554 being exploited?

There is no known exploitation of CVE-2026-23554 in the wild and no public exploit code.

## Other vulnerabilities in Xen Xen

- [CVE-2017-10912](https://insights.sbomify.com/CVE-2017-10912/): Privilege escalation in n/a (critical 10.0)
- [CVE-2017-10918](https://insights.sbomify.com/CVE-2017-10918/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10920](https://insights.sbomify.com/CVE-2017-10920/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10921](https://insights.sbomify.com/CVE-2017-10921/): Memory corruption in n/a (critical 10.0)
- [CVE-2025-27466](https://insights.sbomify.com/CVE-2025-27466/): Mutiple vulnerabilities in the Viridian interface (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23554 and fix it if it is affected.

What it is: CVE-2026-23554 is a high-severity use after free vulnerability in Xen Xen, published on 23 Mar 2026. 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-2026-23554 in the wild and no public exploit code.

Affected product: Xen 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-2026-23554/ (Markdown: https://insights.sbomify.com/CVE-2026-23554/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23554
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23554
- OSV: https://osv.dev/vulnerability/CVE-2026-23554

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23554/
Summaries are generated and may contain mistakes; the official description above is the record.