CVE-2020-27835

Local system crash via stale mm pointer

Published Jan 7, 2021 · Updated Aug 4, 2024

Use-after-free in the Linux Kernel hfi1 driver before 5.10-rc6 allows local users to crash the system through ioctl calls after fork. The driver caches current->mm when an hfi1 device file is opened, but a forked child can inherit the descriptor and use the parent's memory context after its reference is released. Access to an hfi1 device file and high local privileges are required, and the bounded reported consequence is a kernel crash.

CVSS severity4.4
Medium
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux Kernel hfi1 driver before 5.10-rc6 allows local users to crash the system through ioctl calls after fork. The driver caches current->mm when an hfi1 device file is opened, but a forked child can inherit the descriptor and use the parent's memory context after its reference is released. Access to an hfi1 device file and high local privileges are required, and the bounded reported consequence is a kernel crash.

The record

CVE
CVE-2020-27835
Published
Jan 7, 2021
Updated
Aug 4, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jan 7, 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=kernel versions prior to 5.10-rc6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linux Kernelversion=kernel versions prior to 5.10-rc6

Published CVSS scores

4.4NIST NVDCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
6.7SUSECVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
4.9NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:C

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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