CVE-2020-10566Public exploit

Guest-to-host escalation via PFF2 length overflow

Published Mar 14, 2020 · Updated Aug 4, 2024

Buffer overflow in grub2-bhyve before 0.40_8 allows guest OS users to escalate privileges to the FreeBSD host via a crafted PFF2 font. The read_section_as_string function adds one to an untrusted 32-bit section length, wraps the allocation to zero, then copies the much larger section into the undersized heap buffer. The guest must control grub.cfg and reboot the VM; the published proof of concept demonstrates a host-side SIGBUS crash, while VuXML states the corruption can lead to guest-to-host privilege escalation.

CVSS severity7.8
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in grub2-bhyve before 0.40_8 allows guest OS users to escalate privileges to the FreeBSD host via a crafted PFF2 font. The read_section_as_string function adds one to an untrusted 32-bit section length, wraps the allocation to zero, then copies the much larger section into the undersized heap buffer. The guest must control grub.cfg and reboot the VM; the published proof of concept demonstrates a host-side SIGBUS crash, while VuXML states the corruption can lead to guest-to-host privilege escalation.

The record

CVE
CVE-2020-10566
Published
Mar 14, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 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

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

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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 exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499.004Application or System Exploitation

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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