CVE WatchAug 26, 2026

CVE-2021-28691

Guest triggered use-after-free in Linux xen-netback A malicious or buggy network PV frontend can force Linux netback to disable the interfac

CVSS

7.8

High

EPSS

0.4%

p30

KEV

—

Exploit Today

0-100

Published: Jun 29, 2021 · Last modified: Aug 26, 2026 · CWE-416

EPSS · 30d

0.4%EPSS · 30 days0.4%

2026-08-202026-09-17

Technical description

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.

Official references

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