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CVE-2021-28691

Affected software2 products, listed below
Severity7.8 High CVSS 3.1 2 scores
WeaknessUse after free (CWE-416)
Published29 Jun 2021
Updated26 Aug 2026

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.

Exploitation status

No public exploit

No exploit has been reported in the sources we check. Published 5 years ago.

  • CISA KEV not listed
  • VulnCheck KEV not listed
  • CISA Vulnrichment no assessment published
  • Indexed PoC none indexed
  • EPSS 0.36% chance in 30 days

Waratek protection

Outside Waratek scope

A Java vulnerability, but not one Waratek protects. It affects only Java on a user's desktop (applets, Web Start, JavaFX, the installer), sits in a product the Waratek agent can't be installed into, or is in a package we don't expect in business applications. The decision below says which.

  • Protection none
  • Action not pursued none
  • Review automated Upstream data
  • Record active
Decided by The only affected product being a sealed appliance image, where Java runs but no -javaagent can be attached
Finding This CVE names only products the Waratek agent cannot be installed into (netapp/cloud_backup). They ship as sealed appliance images or as native code with no application JVM, so there is no start-up line to add -javaagent to. The vulnerability may well be a Java one; it is permanently out of ARMR's reach rather than outside its subject.

CVSS

7.8 HIGH v3.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H 2 metrics

We show the highest score from the newest CVSS version. Scores from different versions can't be compared, and the first score listed is sometimes a 0.0 placeholder.

VersionScoreBandVectorAssignerType
CVSS 3.1 7.8 HIGH CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H NVD Primary published
CVSS 2.0 4.6 none AV:L/AC:L/Au:N/C:P/I:P/A:P NVD Primary

Affected software and releases

Products and versions

11 products, 11 version entries
SourceVendorProductSchemeAffected versions
nvd linux linux kernel generic ≥ 5.5.0 and < 5.10.43
nvd netapp cloud backup generic any version
nvd netapp h300e firmware generic any version
nvd netapp h300s firmware generic any version
nvd netapp h410c firmware generic any version
nvd netapp h410s firmware generic any version
nvd netapp h500e firmware generic any version
nvd netapp h500s firmware generic any version
nvd netapp h700e firmware generic any version
nvd netapp h700s firmware generic any version
nvd netapp solidfire baseboard management controller generic any version

References

URLTags
https://security.gentoo.org/glsa/202107-30 Third Party Advisory
https://security.netapp.com/advisory/ntap-20210805-0002/ Third Party Advisory
https://xenbits.xenproject.org/xsa/advisory-374.txt Third Party Advisory

Timeline

Published2021-06-29By the CVE Program.
NVD record modified2026-08-26NVD's own last-modified date for this record.