CVE-2020-35503Public exploit

Host process crash via unchecked SCSI frame

Published Jun 2, 2021 · Updated Aug 4, 2024

NULL pointer dereference in QEMU 6.0 and earlier allows guest OS users with elevated privileges to crash the host QEMU process. The megasas_command_cancelled() callback dereferences cmd->frame->header while canceling a SCSI request without first checking whether cmd->frame is NULL. Exploitation requires a privileged guest using megasas-gen2 emulation and interrupts that virtual machine by terminating its host process.

CVSS severity6.0
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in QEMU 6.0 and earlier allows guest OS users with elevated privileges to crash the host QEMU process. The megasas_command_cancelled() callback dereferences cmd->frame->header while canceling a SCSI request without first checking whether cmd->frame is NULL. Exploitation requires a privileged guest using megasas-gen2 emulation and interrupts that virtual machine by terminating its host process.

The record

CVE
CVE-2020-35503
Published
Jun 2, 2021
Updated
Aug 4, 2024
Vendor
QEMU Project
Product
QEMU
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jun 2, 2021CVE 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?

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

  1. Affected versionversion=All QEMU versions before and including 6.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

QEMU Project · QEMUversion=All QEMU versions before and including 6.0

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.0NVDCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H
2.1NVDAV:L/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
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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