CVE-2019-20908: Medium severity Linux Linux kernel vulnerability
A flaw was found in how the ACPI table loading through the EFI variable (and the related efivarssdt boot option) was handled when the Linux kernel was locked down. This flaw allows a (root) privileged local user to circumvent the kernel lockdown restrictions. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Other sources
A flaw was found in the way ACPI table loading through EFI variable (and related efivarssdt 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.
— Red Hat
An issue was discovered in drivers/firmware/efi/efi.c in the Linux kernel before 5.4. Incorrect access permissions for the efivarssdt ACPI variable could be used by attackers to bypass lockdown or secure boot restrictions, aka CID-1957a85b0032.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
redhat/kernel-rtto a version that resolves this vulnerability.Fixed in 0:4.18.0-193.14.3.rt13.67.el8_2 - Upgrade
Upgrade
redhat/kernelto a version that resolves this vulnerability.Fixed in 0:4.18.0-193.14.3.el8_2 - Upgrade
Upgrade
redhat/kernelto a version that resolves this vulnerability.Fixed in 0:4.18.0-80.27.2.el8_0 - Upgrade
Upgrade
redhat/kernelto a version that resolves this vulnerability.Fixed in 0:4.18.0-147.24.2.el8_1 - Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 5.10.223-1Fixed in 5.10.262-1Fixed in 6.1.176-1Fixed in 6.1.180-1Fixed in 6.12.94-1Fixed in 6.12.101-1Fixed in 7.1.8-1Fixed in 7.1.8-2
Event History
Parent advisories
This vulnerability appears in the following advisories.
Frequently Asked Questions
What is the severity of CVE-2019-20908?
CVE-2019-20908 is considered a high-severity vulnerability due to its potential to allow a privileged local user to bypass kernel lockdown restrictions.
How do I fix CVE-2019-20908?
To fix CVE-2019-20908, update to the latest versions of the kernel, specifically versions 0:4.18.0-193.14.3.rt13.67.el8_2 for Red Hat or the corresponding patched versions for Ubuntu and Debian.
Who is affected by CVE-2019-20908?
CVE-2019-20908 affects users of the Linux kernel, particularly those running specific vulnerable versions across various distributions such as Red Hat, Ubuntu, and openSUSE.
What are the common symptoms of CVE-2019-20908 exploitation?
There may be no visible symptoms for CVE-2019-20908 exploitation, as it allows unauthorized access to kernel functions when the system is running in a locked state.
Can CVE-2019-20908 be exploited remotely?
CVE-2019-20908 cannot be exploited remotely; it requires local root privileges to circumvent kernel lockdown protections.