SB2020090930 - Privilege escalation in NFS client in Linux kernel
Published: September 9, 2020 Updated: March 12, 2021
Security Bulletin ID
SB2020090930
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Local access
Highest impact
Code execution
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Time-of-check Time-of-use (TOCTOU) Race Condition (CVE-ID: CVE-2020-25212)
CWE-ID: CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition
CVSSv4: 8.5 [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]
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.Remediation
Install update from vendor's website.
References
- 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/