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CVE-2021-47259

7.8 · HIGH

In the Linux kernel, the following vulnerability has been resolved: NFS: Fix use-after-free in nfs4_init_client() KASAN reports a use-after-free when attempting to mount two different exports thr…

Published May 21, 2024CWE-416EPSS 0.71%

Overview

CVE-2021-47259 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:

NFS: Fix use-after-free in nfs4_init_client()

KASAN reports a use-after-free when attempting to mount two different

exports through two different NICs that belong to the same server.

Olga was able to hit this with kernels starting somewhere between 5.7

and 5.10, but I traced the patch that introduced the clear_bit() call to

4.13. So something must have changed in the refcounting of the clp

pointer to make this call to nfs_put_client() the very last one.

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/3e3c7ebbfac152d08be75c92802a64a1f6471a15Refgit.kernel.org/stable/c/42c10b0db064e45f5c5ae7019bbf2168ffab766cRefgit.kernel.org/stable/c/476bdb04c501fc64bf3b8464ffddefc8dbe01577Refgit.kernel.org/stable/c/72651c6579a25317a90536181d311c663d0329abRefgit.kernel.org/stable/c/c3b6cf64dfe4ef96e7341508d50d6998da7062c7Refgit.kernel.org/stable/c/c7eab9e2d7b4e983ce280276fb920af649955897Refgit.kernel.org/stable/c/3e3c7ebbfac152d08be75c92802a64a1f6471a15Refgit.kernel.org/stable/c/42c10b0db064e45f5c5ae7019bbf2168ffab766cRefgit.kernel.org/stable/c/476bdb04c501fc64bf3b8464ffddefc8dbe01577Refgit.kernel.org/stable/c/72651c6579a25317a90536181d311c663d0329ab

How CyberStrike helps

Frequently asked questions

What is CVE-2021-47259?

CVE-2021-47259 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-2021-47259?

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-2021-47259?

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-2021-47259?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47259 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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