#VU66588 Race condition in Linux kernel - CVE-2020-36557

Vulnerability identifier: #VU66588

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-2020-36557

CWE-ID: CWE-362

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 race condition between the VT_DISALLOCATE IOCTL and closing/opening of ttys. A local user can exploit the race and gain unauthorized access to sensitive information and escalate privileges on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.6.2, 5.6.2

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External links
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.6.2
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ca4463bf8438b403596edd0ec961ca0d4fbe0220

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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.