SB2021052641 - Privilege escalation in Linux kernel KVM
Published: May 26, 2021 Updated: August 20, 2021
Security Bulletin ID
SB2021052641
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 security vulnerability.
1) Buffer overflow (CVE-ID: CVE-2021-22543)
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a boundary error in Linux kernel when handling VM_IO|VM_PFNMAP vmas in KVM. A local user can can bypass RO checks and cause the pages to get freed while still accessible by the VMM and guest. As a result, an attacker with the ability to start and control a VM to read/write random pages of memory, can trigger memory corruption and execute arbitrary code with elevated privileges.
Remediation
Install update from vendor's website.
References
- https://github.com/google/security-research/security/advisories/GHSA-7wq5-phmq-m584
- http://www.openwall.com/lists/oss-security/2021/06/26/1
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ROQIXQB7ZAWI3KSGSHR6H5RDUWZI775S/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/4G5YBUVEPHZYXMKNGBZ3S6INFCTEEL4E/