CVE-2021-4093
First published: Thu Dec 02 2021(Updated: )
A flaw was found in the KVM's AMD code for supporting the Secure Encrypted Virtualization-Encrypted State (SEV-ES). A KVM guest using SEV-ES can trigger out-of-bounds reads and writes in the host kernel via a malicious VMGEXIT for a string I/O instruction (for example, outs or ins) using the exit reason SVM_EXIT_IOIO. This issue results in a crash of the entire system or a potential guest-to-host escape scenario.
Credit: secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| redhat/kernel | <5.15 | 5.15 |
| debian/linux | 5.10.223-1 5.10.226-1 6.1.123-1 6.1.128-1 6.12.12-1 6.12.15-1 | |
| Linux Kernel | >=5.11<5.14.16 | |
| Red Hat Enterprise Linux | =8.0 | |
| Fedora | =35 | |
| Ubuntu | =20.04 | |
| Ubuntu | =21.10 |
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Reference Links
- https://bugs.chromium.org/p/project-zero/issues/detail?id=2222
- https://bugzilla.redhat.com/show_bug.cgi?id=2028584
- https://launchpad.net/bugs/cve/CVE-2021-4093
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2028585
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=95e16b4
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b599840
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0d33b1b
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ea724ea
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3b27de2
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6b5efc9
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4fa4b38
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9b0971c
- http://lkml.iu.edu/hypermail/linux/kernel/2010.1/05072.html
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2028584#c0
- https://git.kernel.org/linus/95e16b4792b0429f1933872f743410f00e590c55
- https://security-tracker.debian.org/tracker/CVE-2021-4093
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-4093
- https://nvd.nist.gov/vuln/detail/CVE-2021-4093
- https://ubuntu.com/security/CVE-2021-4093
Frequently Asked Questions
What is the severity of CVE-2021-4093?
CVE-2021-4093 has been classified with a high severity rating due to the potential for out-of-bounds reads and writes in the host kernel.
How do I fix CVE-2021-4093?
To fix CVE-2021-4093, ensure your system is updated to kernel version 5.15 or later, or apply the specific patches available for your distribution.
What systems are affected by CVE-2021-4093?
CVE-2021-4093 affects various systems including Red Hat Enterprise Linux 8.0, Fedora 35, and specific versions of Ubuntu Linux.
Can CVE-2021-4093 lead to remote code execution?
Yes, CVE-2021-4093 can potentially allow an attacker to exploit the vulnerability to execute arbitrary code on the host system.
Who is responsible for addressing CVE-2021-4093?
It is the responsibility of system administrators and vendors to monitor for patches and updates related to CVE-2021-4093 to ensure systems remain secure.
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