#VU104501 Use-after-free in Linux kernel - CVE-2021-47639

Vulnerability identifier: #VU104501

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-2021-47639

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 kvm_tdp_mmu_put_root(), tdp_mmu_next_root(), kvm_tdp_mmu_wrprot_slot(), kvm_tdp_mmu_clear_dirty_slot() and kvm_tdp_mmu_zap_collapsible_sptes() functions in arch/x86/kvm/mmu/tdp_mmu.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/0c8a8da182d4333d9bbb9131d765145568c847b2
https://git.kernel.org/stable/c/8cf6f98ab1d16d5e607635a0c21c4231eb15367e
https://git.kernel.org/stable/c/af47248407c0c5ae52a752af1ab5ce5b0db91502
https://git.kernel.org/stable/c/d62007edf01f5c11f75d0f4b1e538fc52a5b1982

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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.