CVE-2020-9856Public exploit

Kernel privilege escalation via CVM cache heap overflow

Published Jun 9, 2020 · Updated Aug 4, 2024

Heap-based buffer overflow in Apple macOS before Catalina 10.15.5 allows local users to execute code with kernel privileges. Core Virtual Machine Service cache handling copies user-supplied data into a heap buffer without first validating its length. Exploitation requires low-privileged code execution on the Mac and can elevate that code into the kernel context.

CVSS severity5.3
Medium
EPSS probability1.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in Apple macOS before Catalina 10.15.5 allows local users to execute code with kernel privileges. Core Virtual Machine Service cache handling copies user-supplied data into a heap buffer without first validating its length. Exploitation requires low-privileged code execution on the Mac and can elevate that code into the kernel context.

The record

CVE
CVE-2020-9856
Published
Jun 9, 2020
Updated
Aug 4, 2024
Vendor
Apple
Product
macOS
Classifications
T1068
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Jun 9, 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

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

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <macOS Catalina 10.15.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Apple · macOSversion=unspecified <macOS Catalina 10.15.5

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

Public exploit references

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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