A flaw was found in the way ACPI table loading through EFI variable (and related efivar_ssdt boot option) was handled when the Linux kernel was locked down. A (root) privileged local user could use this flaw to circumvent the kernel lockdown restrictions.
Mitigation: Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Statement: This issue is rated as having Moderate impact because of the privileges required for exploitation.
Created kernel tracking bugs for this issue: Affects: fedora-all [bug 1852944]
External References: https://www.openwall.com/lists/oss-security/2020/06/14/1 https://git.zx2c4.com/american-unsigned-language/tree/american-unsigned-language.sh https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1957a85b0032a81e6482ca4aab883643b8dae06e https://lore.kernel.org/linux-efi/20200615202408.2242614-1-pjones@redhat.com/
*** Bug 1857859 has been marked as a duplicate of this bug. ***
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2020:3218 https://access.redhat.com/errata/RHSA-2020:3218
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2020:3219 https://access.redhat.com/errata/RHSA-2020:3219
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2019-20908
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.1 Extended Update Support Via RHSA-2020:3222 https://access.redhat.com/errata/RHSA-2020:3222
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.0 Update Services for SAP Solutions Via RHSA-2020:3228 https://access.redhat.com/errata/RHSA-2020:3228