Is CVE-2026-102704 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-102704 being exploited in the wild.

How severe is CVE-2026-102704?

Informational severity, published 4 November 2026.

Which products and versions are affected?

Xen Project Xen 4.6 through 4.19.x.

Is there a fix for CVE-2026-102704?

Yes: fixed in Patches available for Xen 4.18.x, 4.17.x, and 4.19.x via xsa523-1.patch, xsa523-2.patch, xsa523-4.18-1.patch, and xsa523-4.18-2.patch. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-102704 attacked?

It is attacked with local access, in an operating system.

Am I affected by CVE-2026-102704?

Check whether you run Xen Project Xen at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

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

CVE-2026-102704 · Severity: info · Published 2026-11-04

Xen is a virtualization platform that isolates guest operating systems on shared hardware. A flaw in how Xen caches permission checks during memory copy operations between virtual machines allows a malicious guest to read and write arbitrary memory belonging to other guests, including the privileged management domain. An attacker with guest access can escape isolation and compromise the entire system.

Technologies: Xen Project Xen. Vendors: Xen Project.

Quick answers

Is CVE-2026-102704 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-102704 being exploited in the wild.
How severe is CVE-2026-102704?: Informational severity, published 4 November 2026.
Which products and versions are affected?: Xen Project Xen 4.6 through 4.19.x.
Is there a fix for CVE-2026-102704?: Yes: fixed in Patches available for Xen 4.18.x, 4.17.x, and 4.19.x via xsa523-1.patch, xsa523-2.patch, xsa523-4.18-1.patch, and xsa523-4.18-2.patch. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-102704 attacked?: It is attacked with local access, in an operating system.
Am I affected by CVE-2026-102704?: Check whether you run Xen Project Xen at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: Patches available for Xen 4.18.x, 4.17.x, and 4.19.x via xsa523-1.patch, xsa523-2.patch, xsa523-4.18-1.patch, and xsa523-4.18-2.patch

Technical details

The vulnerability exists in Xen's grant copy implementation, which caches validation details to optimize batch operations on adjacent memory ranges. Two related flaws occur: frame numbers and grant references can be confused when reusing cached data, and a permission check preventing non-privileged frame-number copies was misplaced, allowing guests to copy from memory they do not own. The attack requires only guest-level access and no user interaction.

Affected products

Xen Project Xen 4.6 through 4.19.x

Timeline

2026-11-03: disclosed
2026-11-04: advisory

References

https://xenbits.xenproject.org/xsa/advisory-523.html

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