Time-of-check Time-of-use (TOCTOU) Race Condition in Linux kernel - CVE-2020-25212

Vulnerability identifier: #VU51433

CSH Severity: Low

CVSSv4.0: 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-2020-25212

CWE-ID: CWE-367

Exploitation vector: Local access

Exploit availability: No public exploit available

Vulnerable software:
Linux kernel

Software vendor:
Linux Foundation

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

The vulnerability exists due to a TOCTOU mismatch in the NFS client code in the Linux kernel. A local user can run a specially crafted program to trigger memory corruption and execute arbitrary code on the system with elevated privileges.

Install updates from vendor's website.

• http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00021.html
• http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00035.html
• http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00042.html
• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.8.3
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b4487b93545214a9db8cbf32e86411677b0cca21
• https://lists.debian.org/debian-lts-announce/2020/09/msg00025.html
• https://lists.debian.org/debian-lts-announce/2020/10/msg00032.html
• https://lists.debian.org/debian-lts-announce/2020/10/msg00034.html
• https://twitter.com/grsecurity/status/1303370421958578179
• https://usn.ubuntu.com/4525-1/
• https://usn.ubuntu.com/4527-1/
• https://usn.ubuntu.com/4578-1/