Bug 2570538 (CVE-2026-99287)

Summary: CVE-2026-99287 kernel: kernel: xen-netback: Denial of Service via double unmapping of shared data rings
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the Linux kernel's Xen network backend (xen-netback) driver. When an error occurs while mapping communication rings for a guest domain, the driver fails to clear the ring pointers after unmapping them, causing the cleanup routine to unmap the same memory pointers a second time. A malicious guest domain can exploit this issue during connection handling to trigger memory corruption, resulting in a host system crash and Denial of Service (DoS).
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Description OSIDB Bzimport 2026-11-10 20:05:39 UTC 
In the Linux kernel, the following vulnerability has been resolved:

xen-netback: Zero out sring pointers on unmap

If xenvif_map_frontend_data_rings() fails when a ring is already mapped,
it unmaps them via xenvif_unmap_frontend_data_rings() which keeps the
ring pointers unchanged. xenvif_connect_data()'s cleanup path calls
xenvif_disconnect_queue() which in turn calls
xenvif_unmap_frontend_data_rings() again, which will attempt to unmap the
pointers a second time.

Zero out the ring pointers after they are unmapped to avoid this issue.

This is XSA-532