Ubuntu Security Notice 5120-1 - It was discovered that the f2fs file system in the Linux kernel did not properly validate metadata in some situations. An attacker could use this to construct a malicious f2fs image that, when mounted and operated on, could cause a denial of service or possibly execute arbitrary code. It was discovered that the Linux kernel did not properly enforce certain types of entries in the Secure Boot Forbidden Signature Database protection mechanism. An attacker could use this to bypass UEFI Secure Boot restrictions. Various other issues were also addressed.
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Ubuntu Security Notice 5071-2 - USN-5071-1 fixed vulnerabilities in the Linux kernel for Ubuntu 20.04 LTS. This update provides the corresponding updates for the Linux Hardware Enablement kernel from Ubuntu 20.04 LTS for Ubuntu 18.04 LTS. 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. Various other issues were also addressed.
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Ubuntu Security Notice 5071-1 - 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. 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. Various other issues were also addressed.
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Debian Linux Security Advisory 4941-1 - Several vulnerabilities have been discovered in the Linux kernel that may lead to a privilege escalation, denial of service or information leaks.
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