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CVE-2021-47439

5.5 · MEDIUM

In the Linux kernel, the following vulnerability has been resolved: net: dsa: microchip: Added the condition for scheduling ksz_mib_read_work When the ksz module is installed and removed using rm…

Published May 22, 2024CWE-476EPSS 0.22%

Overview

CVE-2021-47439 is a medium-severity vulnerability. It was published on May 22, 2024 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

net: dsa: microchip: Added the condition for scheduling ksz_mib_read_work

When the ksz module is installed and removed using rmmod, kernel crashes

with null pointer dereferrence error. During rmmod, ksz_switch_remove

function tries to cancel the mib_read_workqueue using

cancel_delayed_work_sync routine and unregister switch from dsa.

During dsa_unregister_switch it calls ksz_mac_link_down, which in turn

reschedules the workqueue since mib_interval is non-zero.

Due to which queue executed after mib_interval and it tries to access

dp->slave. But the slave is unregistered in the ksz_switch_remove

function. Hence kernel crashes.

To avoid this crash, before canceling the workqueue, resetted the

mib_interval to 0.

v1 -> v2:

-Removed the if condition in ksz_mib_read_work

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/383239a33cf29ebee9ce0d4e0e5c900b77a16148Refgit.kernel.org/stable/c/ef1100ef20f29aec4e62abeccdb5bdbebba1e378Refgit.kernel.org/stable/c/f2e1de075018cf71bcd7d628e9f759cb8540b0c3Refgit.kernel.org/stable/c/383239a33cf29ebee9ce0d4e0e5c900b77a16148Refgit.kernel.org/stable/c/ef1100ef20f29aec4e62abeccdb5bdbebba1e378Refgit.kernel.org/stable/c/f2e1de075018cf71bcd7d628e9f759cb8540b0c3

How CyberStrike helps

Frequently asked questions

What is CVE-2021-47439?

CVE-2021-47439 is a medium-severity vulnerability. It was published on May 22, 2024 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47439?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-47439?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-47439?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47439 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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