CVE-2020-11739

Hypervisor memory disclosure or crash via unlock race

Published Apr 14, 2020 · Updated Aug 4, 2024

Race condition in Xen through 4.13.x allows guest OS users to disclose hypervisor memory or crash an Arm host via concurrent hypercalls. Xen's read-write unlock paths omit a memory barrier, allowing an Arm processor to expose the lock before preceding critical-section accesses complete. Exploitation requires control of a guest and an Arm CPU with susceptible memory-reordering behavior; x86 hosts are not affected.

CVSS severity7.8
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Xen through 4.13.x allows guest OS users to disclose hypervisor memory or crash an Arm host via concurrent hypercalls. Xen's read-write unlock paths omit a memory barrier, allowing an Arm processor to expose the lock before preceding critical-section accesses complete. Exploitation requires control of a guest and an Arm CPU with susceptible memory-reordering behavior; x86 hosts are not affected.

The record

CVE
CVE-2020-11739
Published
Apr 14, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-362, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 14, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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

6.9NIST NVDAV:L/AC:M/Au:N/C:C/I:C/A:C
7.8NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

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

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1499Endpoint Denial of Service

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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