# CVE-2026-102699: Xen hypervisor calculation underflow in GNTTABOP_cache_flush on Arm

Source: https://junglewise.ai/threats/cve-2026-102699-this-cna-information-record-relates-to-multiple-cves-the-text  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-102699 · Severity: info · Published 2026-10-13

Xen is a hypervisor that manages virtual machines on a server. A flaw in the grant table interface allows a guest to corrupt memory belonging to another guest by performing cache invalidation operations on read-only memory mappings. This could lead to privilege escalation, data exposure, or service disruption across virtual machines sharing the hypervisor.

Vendors: [Xen](https://junglewise.ai/threats/vendors/xen).

## Quick answers

**Is CVE-2026-102699 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-102699 being exploited in the wild.

**How severe is CVE-2026-102699?** Informational severity, published 13 October 2026.

**Which products and versions are affected?** Xen Hypervisor 4.5 through 4.21.x on Arm platforms.

**Is there a fix for CVE-2026-102699?** No fixed version is recorded yet. There is no known mitigation; patching is required.</anigation>
<parameter name="fixed_in">Xen 4.21.x (via xsa519-1.patch and xsa519-2.patch), Xen 4.20.x through 4.17.x (via xsa519-4.20-1.patch and xsa519-4.20-2.patch)</anitation>
</invoke> If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-102699 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-102699?** Check whether you run Xen Hypervisor 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


There is no known mitigation; patching is required.</anigation>
<parameter name="fixed_in">Xen 4.21.x (via xsa519-1.patch and xsa519-2.patch), Xen 4.20.x through 4.17.x (via xsa519-4.20-1.patch and xsa519-4.20-2.patch)</anitation>
</invoke>

## Technical details

CVE-2026-102702 is a logic error in GNTTABOP_cache_flush on Arm systems where the operation does not properly restrict invalidate-without-clean operations against read-only grant table mappings from other domains. An unprivileged guest can corrupt memory in another domain by issuing these operations, potentially enabling privilege escalation or information disclosure attacks.

## Affected products

- Xen Hypervisor 4.5 through 4.21.x on Arm platforms

## Timeline

- 2026-10-13: disclosed

## References

- [https://xenbits.xenproject.org/xsa/advisory-519.html](https://xenbits.xenproject.org/xsa/advisory-519.html)