#VU90052 Use-after-free in Linux kernel - CVE-2021-47506

Vulnerability identifier: #VU90052

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-47506

CWE-ID: CWE-416

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a use-after-free error within the hash_delegation_locked(), unhash_delegation_locked() and nfsd4_cb_recall_prepare() functions in fs/nfsd/nfs4state.c. A local user can escalate privileges on the system.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: All versions

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External links
https://git.kernel.org/stable/c/04a8d07f3d58308b92630045560799a3faa3ebce
https://git.kernel.org/stable/c/348714018139c39533c55661a0c7c990671396b4
https://git.kernel.org/stable/c/33645d3e22720cac1e4548f8fef57bf0649536ee
https://git.kernel.org/stable/c/2becaa990b93cbd2928292c0b669d3abb6cf06d4
https://git.kernel.org/stable/c/e0759696de6851d7536efddfdd2dfed4c4df1f09
https://git.kernel.org/stable/c/eeb0711801f5e19ef654371b627682aed3b11373
https://git.kernel.org/stable/c/148c816f10fd11df27ca6a9b3238cdd42fa72cd3
https://git.kernel.org/stable/c/548ec0805c399c65ed66c6641be467f717833ab5

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.