CVE-2021-26934

Unspecified impact via unsupported backend allocation mode

Published Feb 17, 2021 · Updated Aug 3, 2024

Unsupported backend allocation in Linux kernel 4.18 through 5.10.16 causes unspecified impacts when used by Xen guests. The drm_xen_front support-status entry fails to mark backend allocation, or be-alloc, as unsupported even though that configuration was never intended to work. Reachability requires a Xen guest to use the affected driver in backend-allocation mode; Xen reports only unknown effects and identifies no concrete consequence.

CVSS severity7.8
High
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unsupported backend allocation in Linux kernel 4.18 through 5.10.16 causes unspecified impacts when used by Xen guests. The drm_xen_front support-status entry fails to mark backend allocation, or be-alloc, as unsupported even though that configuration was never intended to work. Reachability requires a Xen guest to use the affected driver in backend-allocation mode; Xen reports only unknown effects and identifies no concrete consequence.

The record

CVE
CVE-2021-26934
Published
Feb 17, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
Unavailable
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

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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

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/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

No sourced classifications are available.

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

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Your stack

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