CVE-2021-28691: Linux Kernel

High severity, CVSS 7.8. EPSS: 0.4% chance of exploitation in the next 30 days.

Guest triggered use-after-free in Linux xen-netback A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer.

Affected products

• Linux Linux Kernel: from 5.5.0, before 5.10.43 (fixed in 5.10.43)
• Netapp Cloud Backup: affected versions not specified
• Netapp h300e Firmware: affected versions not specified
• Netapp h300s Firmware: affected versions not specified
• Netapp h410c Firmware: affected versions not specified
• Netapp h410s Firmware: affected versions not specified
• Netapp h500e Firmware: affected versions not specified
• Netapp h500s Firmware: affected versions not specified
• Netapp h700e Firmware: affected versions not specified
• Netapp h700s Firmware: affected versions not specified
• Netapp Solidfire Baseboard Management Controller: affected versions not specified

Published 2021-06-29. Last modified 2026-08-26.