Bug 2568422 (CVE-2026-100080)

Summary:	CVE-2026-100080 kernel: kernel: xen-netback: Denial of Service via use-after-free during queue teardown
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in the Linux kernel's xen-netback driver. When handling a connection error caused by invalid guest configuration data, network queue statistics memory is freed without proper synchronization. If the statistics data is concurrently read through the system file system, a use-after-free condition can occur. This flaw may allow a malicious guest domain to cause a Denial of Service (DoS) by crashing the host system, leak sensitive information, or potentially execute arbitrary code.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2026-11-06 18:31:24 UTC

In the Linux kernel, the following vulnerability has been resolved:

xen-netback: Fix UAF when reading statistics data

The network statistic data in the driver is protected by RCU.
Unfortunately when tearing down the queues after an error during
connecting to the frontend (e.g. due to illegal Xenstore data filled
in by the guest), the statistic data is being freed without
synchronizing the RCU state.  In case the data is being read via sysfs
in this phase, access to already freed memory or memory being in new
use is possible.

Fix that by calling synchronize_net() before freeing the queue data.

This is XSA-526 / CVE-2026-100080