# CVE-2026-99286: Linux kernel xen-netback race condition in XenBus disconnect

Source: https://junglewise.ai/threats/cve-2026-99286-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-99286 · Severity: info · Published 2026-11-10

A race condition exists in the Linux kernel's xen-netback driver during XenBus connection failure cleanup. When statistics functions read queue information concurrently with cleanup operations, they may attempt to access invalid queue structures, potentially causing a kernel crash or undefined behavior. This affects systems using Xen virtualization with network backend drivers.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux).

## Quick answers

**Is CVE-2026-99286 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-99286 being exploited in the wild.

**How severe is CVE-2026-99286?** Informational severity, published 10 November 2026.

**Which products and versions are affected?** Linux Kernel multiple versions prior to fix.

**Is there a fix for CVE-2026-99286?** No fixed version is recorded yet. Check the vendor's advisory in the references below. 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-2026-99286 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-99286?** Check whether you run Linux Kernel 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

The vulnerability is a use-after-free race condition in xen-netback's xenbus.c where xenvif_get_stats and xenvif_get_ethtool_stats capture vif->num_queues under RCU read lock. The cleanup code must set vif->num_queues to zero before synchronize_net() to prevent readers from accessing deallocated queue structures. The fix reorders operations to unpublish the queue count prior to synchronization, matching the pattern used in backend_disconnect.

## Affected products

- Linux Linux kernel multiple versions prior to fix

## Timeline

- 2026-11-10: disclosed

## References

- [https://git.kernel.org/stable/c/07aca7d25ce8578fedde49855983a01c537a782b](https://git.kernel.org/stable/c/07aca7d25ce8578fedde49855983a01c537a782b)
- [https://git.kernel.org/stable/c/a97aa838903d15f865d80809f5198ff459c6634a](https://git.kernel.org/stable/c/a97aa838903d15f865d80809f5198ff459c6634a)

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