Summary
Maxim Levitsky and Paolo Bonzini discovered that the KVM hypervisor
implementation for AMD processors in the Linux kernel allowed a guest VM to
disable restrictions on VMLOAD/VMSAVE in a nested guest. An attacker in a
guest VM could use this to read or write portions of the host's physical
memory. (CVE-2021-3656)
Maxim Levitsky discovered that the KVM hypervisor implementation for AMD
processors in the Linux kernel did not properly prevent a guest VM from
enabling AVIC in nested guest VMs. An attacker in a guest VM could use this
to write to portions of the host's physical memory. (CVE-2021-3653)
It was discovered that the Linux kernel did not properly enforce certain
types of entries in the Secure Boot Forbidden Signature Database (aka dbx)
protection mechanism. An attacker could use this to bypass UEFI Secure Boot
restrictions. (CVE-2020-26541)
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. (CVE-2021-22543)
Norbert Slusarek discovered that the CAN broadcast manger (bcm) protocol
implementation in the Linux kernel did not properly initialize memory in
some situations. A local attacker could use this to expose sensitive
information (kernel memory). (CVE-2021-34693)
Murray McAllister discovered that the joystick device interface in the
Linux kernel did not properly validate data passed via an ioctl(). A local
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code on systems with a joystick device
registered. (CVE-2021-3612)
It was discovered that the KVM hypervisor implementation in the Linux
kernel did not properly compute the access permissions for shadow pages in
some situations. A local attacker could use this to cause a denial of
service. (CVE-2021-38198)
It was discovered that the perf subsystem in the Linux kernel for the
PowerPC architecture contained a null pointer dereference in some
situations. An attacker could use this to cause a denial of service (system
crash). (CVE-2021-38200)
Ben Greear discovered that the mac80211 subsystem in the Linux kernel
contained a null pointer dereference in some situations. A physically
proximate attacker could possibly use this to cause a denial of service
(system crash). (CVE-2021-38206)
It was discovered that the Xilinx LL TEMAC device driver in the Linux
kernel did not properly calculate the number of buffers to be used in
certain situations. A remote attacker could use this to cause a denial of
service (system crash). (CVE-2021-38207)
Fixed packages 4
| Release | Package | Fixed in |
|---|---|---|
| Ubuntu · 20.04 LTS 20.04:LTS | linux-aws-5.11 | 5.11.0-1017.18~20.04.1 |
| Ubuntu · 20.04 LTS 20.04:LTS | linux-azure-5.11 | 5.11.0-1015.16~20.04.1 |
| Ubuntu · 20.04 LTS 20.04:LTS | linux-hwe-5.11 | 5.11.0-34.36~20.04.1 |
| Ubuntu · 20.04 LTS 20.04:LTS | linux-oracle-5.11 | 5.11.0-1017.18~20.04.1 |
Vulnerabilities 10
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High 8.7
Improper memory handling in Linux KVM
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 …
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Medium 6.5
The Linux kernel through 5.8.13 does not properly enforce the Secure Boot Forbidden Signature Database (aka dbx) protec…
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Unscored —
net/can/bcm.c in the Linux kernel through 5.12.10 allows local users to obtain sensitive information from kernel stack …
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Unscored —
An out-of-bounds memory write flaw was found in the Linux kernel's joystick devices subsystem in versions before 5.9-rc…
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Unscored —
A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VM…
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Unscored —CVE-2021-3656 Public exploit
A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VM…
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Unscored —
arch/x86/kvm/mmu/paging_tmpl.h in the Linux kernel before 5.12.11 incorrectly computes the access permissions of a shad…
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Unscored —
arch/powerpc/perf/core-book3s.c in the Linux kernel before 5.12.13, on systems with perf_event_paranoid=-1 and no speci…
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Unscored —
The mac80211 subsystem in the Linux kernel before 5.12.13, when a device supporting only 5 GHz is used, allows attacker…
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Unscored —
drivers/net/ethernet/xilinx/ll_temac_main.c in the Linux kernel before 5.12.13 allows remote attackers to cause a denia…
References
-
report
https://ubuntu.com/security/CVE-2020-26541
-
report
https://ubuntu.com/security/CVE-2021-3612
-
report
https://ubuntu.com/security/CVE-2021-3653
-
report
https://ubuntu.com/security/CVE-2021-3656
-
report
https://ubuntu.com/security/CVE-2021-22543
-
report
https://ubuntu.com/security/CVE-2021-34693
-
report
https://ubuntu.com/security/CVE-2021-38198
-
report
https://ubuntu.com/security/CVE-2021-38200
-
report
https://ubuntu.com/security/CVE-2021-38206
-
report
https://ubuntu.com/security/CVE-2021-38207