CVE-2021-22543

Published: 26 May 2021

An issue was discovered in Linux: KVM through Improper handling of VM_IO|VM_PFNMAP vmas in KVM can bypass RO checks and can lead to pages being freed while still accessible by the VMM and guest. This allows users with the ability to start and control a VM to read/write random pages of memory and can result in local privilege escalation.

From the Ubuntu Security Team

It was discovered that the KVM hypervisor implementation in the Linux kernel did not properly perform reference counting in some situations, leading to a use-after-free vulnerability. An attacker who could start and control a VM could possibly use this to expose sensitive information or execute arbitrary code.

Priority

Medium

CVSS 3 base score: 7.8

Status

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-22543
• https://github.com/google/security-research/security/advisories/GHSA-7wq5-phmq-m584
• https://www.openwall.com/lists/oss-security/2021/05/26/3
• https://www.openwall.com/lists/oss-security/2021/05/26/4
• https://www.openwall.com/lists/oss-security/2021/05/26/5
• https://github.com/torvalds/linux/commit/f8be156be163a052a067306417cd0ff679068c97
• https://ubuntu.com/security/notices/USN-5070-1
• https://ubuntu.com/security/notices/USN-5071-1
• https://ubuntu.com/security/notices/USN-5071-2
• https://ubuntu.com/security/notices/USN-5071-3
• https://ubuntu.com/security/notices/USN-5094-1
• https://ubuntu.com/security/notices/USN-5094-2
• https://ubuntu.com/security/notices/USN-5106-1
• https://ubuntu.com/security/notices/USN-5120-1
• NVD
• Launchpad
• Debian