CVE-2021-26932

Backend-domain crash via grant-mapping error mishandling

Published Feb 17, 2021 · Updated Aug 3, 2024

Improper error handling in the Linux kernel 3.2 through 5.10.16 allows guest OS users to crash Xen PV backend domains. Grant-mapping paths in arch/*/xen/p2m.c and drivers/xen/gntdev.c ignore some failed batch elements or skip later results, treating failures as successes or preventing successful mappings from being properly unmapped during recovery. The flaw requires a Linux backend running in PV mode on x86 or on Arm and can crash the backend domain or exhaust its resources, potentially interrupting every guest service hosted by that domain.

CVSS severity5.5
Medium
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper error handling in the Linux kernel 3.2 through 5.10.16 allows guest OS users to crash Xen PV backend domains. Grant-mapping paths in arch/*/xen/p2m.c and drivers/xen/gntdev.c ignore some failed batch elements or skip later results, treating failures as successes or preventing successful mappings from being properly unmapped during recovery. The flaw requires a Linux backend running in PV mode on x86 or on Arm and can crash the backend domain or exhaust its resources, potentially interrupting every guest service hosted by that domain.

The record

CVE
CVE-2021-26932
Published
Feb 17, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 17, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
1.9NIST NVDAV:L/AC:M/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo