# CVE-2026-62432: Xen race condition in FIFO event channel expansion

Source: https://junglewise.ai/threats/cve-2026-62432-xen-race-condition-in-fifo-event-channel-expansion  
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-2026-62432 · Severity: info · CVSS 0 · Published 2026-07-28

A vulnerability in the Xen hypervisor allows a malicious virtual machine to crash the entire physical server. This occurs when the system incorrectly handles internal event communication requests, leading to a system-wide denial of service. While primarily a stability risk, it could disrupt all operations and other virtual machines running on the same hardware.

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

## Quick answers

**Is CVE-2026-62432 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-62432 being exploited in the wild.

**How severe is CVE-2026-62432?** Informational severity, with a CVSS score of 0, published 28 July 2026.

**Which products and versions are affected?** Xen Project Xen 4.5 and later.

**Is there a fix for CVE-2026-62432?** 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-2026-62432 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-62432?** 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 hypervisor between the EVTCHNOP_expand_array and EVTCHNOP_reset hypercalls. The expand_array operation checks if FIFO event channels are enabled without holding the necessary lock, allowing a concurrent reset operation to clear state. This results in a NULL pointer dereference when the expand operation proceeds. For HVM and ARM guests, this leads to a host crash (DoS). For x86 PV guests, while a crash is the most likely outcome, the Xen Project notes that memory corruption or privilege escalation cannot be entirely ruled out. The issue affects Xen versions 4.5 and later.

## Affected products

- Xen Project Xen 4.5 and later

## Timeline

- 2026-07-28: disclosed
- 2026-07-28: advisory
- 2026-07-28: patched

## References

- [https://xenbits.xenproject.org/xsa/advisory-505.html](https://xenbits.xenproject.org/xsa/advisory-505.html)

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