CVE-2021-28691

HIGH
7.8
CVSS Score
Published: June 29, 2021 at 11:30 AM UTC
Updated: August 26, 2026 at 06:11 PM UTC
19 products affected across 2 vendorsLinux KernelCloud BackupH700S Firmware

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Severity
HIGH7.8
Exploit prediction
EPSS 0.4%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≥ 5.5.05.5.0 ≤ v < 5.10.435.5.0
Affected range stops below 5.10.43, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in next of 5.12.2 (unaffected)
Vendor states this is fixed in 4.12 (unknown)
All versions
All versions
netapp-h300e (same device)
All versions
netapp-h300s (same device)
All versions
netapp-h410c (same device)
All versions
netapp-h410s (same device)
All versions
netapp-h500e (same device)
All versions
netapp-h500s (same device)
All versions
netapp-h700e (same device)
All versions
netapp-h700s (same device)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

Vendor Advisoryx_refsource_GENTOOThird Party Advisory
https://security.gentoo.org/glsa/202107-30

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-416

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