CVE-2021-47259

HIGH
Published May 21, 2024 Modified Apr 4, 2025 CWE-416

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.

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CVSS v3.1 Score

7.5
HIGH
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-416 Use After Free

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel

References

Advisories & Patches

https://git.kernel.org/stable/c/3e3c7ebbfac152d08be75c92802a64a1f6471a15 https://git.kernel.org/stable/c/42c10b0db064e45f5c5ae7019bbf2168ffab766c https://git.kernel.org/stable/c/476bdb04c501fc64bf3b8464ffddefc8dbe01577 https://git.kernel.org/stable/c/72651c6579a25317a90536181d311c663d0329ab https://git.kernel.org/stable/c/c3b6cf64dfe4ef96e7341508d50d6998da7062c7 https://git.kernel.org/stable/c/c7eab9e2d7b4e983ce280276fb920af649955897 https://git.kernel.org/stable/c/3e3c7ebbfac152d08be75c92802a64a1f6471a15 https://git.kernel.org/stable/c/42c10b0db064e45f5c5ae7019bbf2168ffab766c https://git.kernel.org/stable/c/476bdb04c501fc64bf3b8464ffddefc8dbe01577 https://git.kernel.org/stable/c/72651c6579a25317a90536181d311c663d0329ab https://git.kernel.org/stable/c/c3b6cf64dfe4ef96e7341508d50d6998da7062c7 https://git.kernel.org/stable/c/c7eab9e2d7b4e983ce280276fb920af649955897

Frequently Asked Questions

What is CVE-2021-47259? +
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. It has a CVSS v3.1 base score of 7.5 (HIGH).
How severe is CVE-2021-47259? +
CVE-2021-47259 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.
What products are affected by CVE-2021-47259? +
CVE-2021-47259 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2021-47259? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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