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Security Advisory

USN-5210-2: Linux kernel regression

Severity

Unknown

Vendor

Canonical Ubuntu

Versions Affected

  • Canonical Ubuntu 18.04

Description

USN-5210-1 fixed vulnerabilities in the Linux kernel. Unfortunately, that update introduced a regression that caused failures to boot in environments with AMD Secure Encrypted Virtualization (SEV) enabled. This update fixes the problem. We apologize for the inconvenience. Original advisory details: Nadav Amit discovered that the hugetlb implementation in the Linux kernel did not perform TLB flushes under certain conditions. A local attacker could use this to leak or alter data from other processes that use huge pages. (CVE-2021-4002) 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 a race condition existed in the overlay file system implementation in the Linux kernel. A local attacker could use this to cause a denial of service (system crash). (CVE-2021-20321) It was discovered that the NFC subsystem in the Linux kernel contained a use-after-free vulnerability in its NFC Controller Interface (NCI) implementation. A local attacker could possibly use this to cause a denial of service (system crash) or execute arbitrary code. (CVE-2021-3760) It was discovered that an integer overflow could be triggered in the eBPF implementation in the Linux kernel when preallocating objects for stack maps. A privileged local attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-41864) It was discovered that the KVM implementation for POWER8 processors in the Linux kernel did not properly keep track if a wakeup event could be resolved by a guest. An attacker in a guest VM could possibly use this to cause a denial of service (host OS crash). (CVE-2021-43056) It was discovered that the ISDN CAPI implementation in the Linux kernel contained a race condition in certain situations that could trigger an array out-of-bounds bug. A privileged local attacker could possibly use this to cause a denial of service or execute arbitrary code. (CVE-2021-43389)

Affected Cloud Foundry Products and Versions

Severity is unknown unless otherwise noted.

  • Bionic Stemcells
    • 1.x versions
    • All other stemcells not listed.

Mitigation

Users of affected products are strongly encouraged to follow the mitigations below. The Cloud Foundry project recommends upgrading the following releases:

  • Bionic Stemcells
    • There are no fixed versions of this product
    • All other stemcells should be upgraded to the latest version available onĀ bosh.io.

References

History

2022-01-20: Initial vulnerability report published.

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Cloud Foundry Foundation Security Team, AUTHOR

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