#VU28167 Use-after-free in Linux kernel - CVE-2020-12657

Vulnerability identifier: #VU28167

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-2020-12657

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 compromise vulnerable system.

The vulnerability exists due to a use-after-free error in "block/bfq-iosched.c" file related to "bfq_idle_slice_timer_body". A local user can execute arbitrary code on the target system.

Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: 5.6 - 5.6.4

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External links
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.6.5
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=2f95fa5c955d0a9987ffdc3a095e2f4e62c5f2a9
https://github.com/torvalds/linux/commit/2f95fa5c955d0a9987ffdc3a095e2f4e62c5f2a9
https://patchwork.kernel.org/patch/11447049/

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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.