# CVE-2026-62436: Xen grant table race condition in version switching

Source: https://junglewise.ai/threats/cve-2026-62436-xen-grant-table-race-condition-in-version-switching  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-28. Updated: 2026-07-28  
License: CC BY 4.0 with a link back

CVE-2026-62436 · Severity: info · CVSS 0 · Published 2026-07-28

A vulnerability exists in the Xen hypervisor, which is software used to run multiple virtual machines on a single physical server. An attacker controlling a virtual machine could exploit a flaw in how the system manages memory sharing to gain full control over the host server. This could lead to the theft of data from other customers, a total system shutdown, or unauthorized access to the underlying infrastructure.

Technologies: [Xen Project Xen](https://junglewise.ai/threats/technologies/xen). Vendors: [Xen Project](https://junglewise.ai/threats/vendors/xen-project).

## Quick answers

**Is CVE-2026-62436 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-62436 being exploited in the wild.

**How severe is CVE-2026-62436?** Informational severity, with a CVSS score of 0, published 28 July 2026.

**Which products and versions are affected?** Xen Project Xen 4.0 and newer.

**Is there a fix for CVE-2026-62436?** A patch was published on 2026-07-28. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-62436 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-62436?** 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.

## Technical details

A race condition exists in the Xen grant table implementation when switching between version 2 and version 1 (CVE-2026-62436). The vulnerability occurs because the code drops and re-acquires the grant table lock, incorrectly assuming that table properties (such as status frames) remain constant during the unlocked window. An unprivileged multi-vCPU x86 guest can exploit this timing window to trigger memory corruption or logic errors. This can result in guest-to-host privilege escalation, information disclosure, or a hypervisor crash. The issue affects all Xen versions from 4.0 onwards, specifically on x86 systems where grant table v2 is enabled.

## Affected products

- Xen Project Xen 4.0 and newer

## Timeline

- 2026-07-28: disclosed: Public release of XSA-501
- 2026-07-28: patched

## References

- [https://xenbits.xenproject.org/xsa/advisory-501.html](https://xenbits.xenproject.org/xsa/advisory-501.html)

## Related threats

- [Xen arbitrary read/write via grant copy caching](https://junglewise.ai/threats/cve-2026-102704-this-cna-information-record-relates-to-multiple-cves-the-text)
- [Xen hypervisor arbitrary read/write via grant copy](https://junglewise.ai/threats/cve-2026-102703-this-cna-information-record-relates-to-multiple-cves-the-text)
- [Xen VMX VMentry failure with branch tracing and blocked states](https://junglewise.ai/threats/cve-2026-79611-for-xsa-308-logic-was-introduced-as-vmx-vmentry-checks-do-not)
- [Xen XPTI privilege escalation on huge-memory systems](https://junglewise.ai/threats/cve-2026-79609-xpti-xen-page-table-isolation-was-introduced-to-mitigate-meltdown)
- [Xen ineffectual Zenbleed workaround on AMD x86](https://junglewise.ai/threats/cve-2026-79608-the-workaround-for-xsa-433-zenbleed-was-later-re-worked-to-better)