CVE-2019-7221: Use After Free
A use after free issue was found in the way Linux kernel's KVM hypervisor emulates a preemption timer for L2 guest when nested(=1) virtualization is enabled. This high resolution timer(hrtimer) runs when L2 guest is active. After VM exit, in syncvmcs12() timer object is stopped. The use-after-free occurs if the timer object is free'd before calling syncvmcs12() routine.
A guest user/process could use this flaw to crash the host kernel resulting in DoS OR potentially gain privileged access to a system.
It affects only Intel processors and only when nested virtualization is enabled.
Upstream patch: --------------- -> https://git.kernel.org/linus/ecec76885bcfe3294685dc363fd1273df0d5d65f
Reference: ---------- -> https://www.openwall.com/lists/oss-security/2019/02/18/2
Other sources
The KVM implementation in the Linux kernel through 4.20.5 has a Use-after-Free.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 5.10.223-1Fixed in 5.10.262-1Fixed in 6.1.176-1Fixed in 6.1.180-1Fixed in 6.12.94-1Fixed in 6.12.101-1Fixed in 7.1.7-1Fixed in 7.1.8-1
Event History
Frequently Asked Questions
What is the severity of CVE-2019-7221?
CVE-2019-7221 has been rated as a high severity vulnerability due to its potential impact on the Linux kernel's KVM hypervisor.
How do I fix CVE-2019-7221?
To resolve CVE-2019-7221, upgrade to a fixed kernel version such as 5.10.223-1 or later.
Which software versions are affected by CVE-2019-7221?
CVE-2019-7221 affects Linux kernel versions up to and including 4.20.5 among various distributions like openSUSE, Fedora, and Ubuntu.
What systems are impacted by CVE-2019-7221?
The systems impacted by CVE-2019-7221 include various Linux distributions and versions that are utilizing the Linux kernel's KVM hypervisor.
What is the exploit type of CVE-2019-7221?
CVE-2019-7221 is classified as a use-after-free vulnerability in the KVM hypervisor.