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CVE-2021-47281

7.8 · HIGH

In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Fix race of snd_seq_timer_open() The timer instance per queue is exclusive, and snd_seq_timer_open() should have man…

Published May 21, 2024CWE-416EPSS 0.24%

Overview

CVE-2021-47281 is a high-severity vulnerability. It was published on May 21, 2024 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. 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:

ALSA: seq: Fix race of snd_seq_timer_open()

The timer instance per queue is exclusive, and snd_seq_timer_open()

should have managed the concurrent accesses. It looks as if it's

checking the already existing timer instance at the beginning, but

it's not right, because there is no protection, hence any later

concurrent call of snd_seq_timer_open() may override the timer

instance easily. This may result in UAF, as the leftover timer

instance can keep running while the queue itself gets closed, as

spotted by syzkaller recently.

For avoiding the race, add a proper check at the assignment of

tmr->timeri again, and return -EBUSY if it's been already registered.

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/536a7646c00a0f14fee49e5e313109e5da2f6031Refgit.kernel.org/stable/c/83e197a8414c0ba545e7e3916ce05f836f349273Refgit.kernel.org/stable/c/bd7d88b0874f82f7b29d1a53e574cedaf23166baRefgit.kernel.org/stable/c/536a7646c00a0f14fee49e5e313109e5da2f6031Refgit.kernel.org/stable/c/83e197a8414c0ba545e7e3916ce05f836f349273Refgit.kernel.org/stable/c/bd7d88b0874f82f7b29d1a53e574cedaf23166ba

How CyberStrike helps

Frequently asked questions

What is CVE-2021-47281?

CVE-2021-47281 is a high-severity vulnerability. It was published on May 21, 2024 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2021-47281?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-47281?

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-2021-47281?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47281 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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