---
id: "CVE-2026-102704"
kind: "vulnerability"
aliases: ["CVE-2026-102704"]
title: "Xen: grant copy check lets a guest copy another domain's memory"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["hypervisor", "infrastructure", "self-hosted", "virtualization", "xen"]
not_affected_if: []
published_at: "2026-11-04T11:17:07+00:00"
first_seen_at: "2026-11-04T11:26:45+00:00"
updated_at: "2026-11-04T11:27:48+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102704", "first_seen_at": "2026-11-04T11:26:45+00:00"}]
---

# Xen: grant copy check lets a guest copy another domain's memory

Xen caches validation data across batches of grant copy operations, and the check that restricts copying by frame number to a caller's own memory is misplaced. A guest may be able to copy memory belonging to other domains, which can expose data across virtual machine boundaries.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-11-04T11:26:45+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-102704

## From the sources

[This CNA information record relates to multiple CVEs; the
text explains which aspects/vulnerabilities correspond to which CVE.]

A common access pattern is a batch of Grant Copy operations acting on
adjacent address ranges in the same source or destination page.  For
performance reasons, Xen caches details internally to reuse already
validated data.  The conditions on when to re-validate the internal data
were not correct in some cases:

 - Frame numbers and grant references could wrongly be mixed up.  This
   is CVE-2026-102703.

 - Copying by frame number (rather than grant reference) is permitted
   only when operating on the caller's own memory.  The check to enforce
   this restriction was misplaced.  This is CVE-2026-102704.

---

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