# CVE-2026-102704: arbitrary read/write via grant copy

Status: published. Published: 2026-11-04. Updated: 2026-11-04.

[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.

## Remediation

- workaround: There is no known mitigation. (source: CNA: XEN)

## Affected products and versions

- Xen / Xen: consult Xen advisory XSA-523 (unknown). Source: CNA: XEN

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://xenbits.xenproject.org/xsa/advisory-523.html (CNA: XEN)

- https://xenbits.xenproject.org/xsa/advisory-523.html (security@xen.org)

## Provenance

- CNA: XEN: https://www.cve.org/CVERecord?id=CVE-2026-102704; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-102704; retrieved 2026-11-04; source updated 2026-11-04

Revision: 59a33c9dc1fa4bfa4bedf1235facb970dcb5b0c6c0c049c871b1df638774fbbe

Canonical: https://y2.dev/cve/CVE-2026-102704

## Agent and API access

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- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

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