Topic

An update for shim, shim-unsigned-aarch64, and shim-unsigned-x64 is now available for Red Hat Enterprise Linux 8.

Red Hat Product Security has rated this update as having a security impact of Moderate. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

The shim package contains a first-stage UEFI boot loader that handles chaining to a trusted full boot loader under secure boot environments.

Security Fix(es):

• grub2: acpi command allows privileged user to load crafted ACPI tables when Secure Boot is enabled (CVE-2020-14372)
• grub2: Use-after-free in rmmod command (CVE-2020-25632)
• grub2: Out-of-bounds write in grub_usb_device_initialize() (CVE-2020-25647)
• grub2: Stack buffer overflow in grub_parser_split_cmdline() (CVE-2020-27749)
• grub2: cutmem command allows privileged user to remove memory regions when Secure Boot is enabled (CVE-2020-27779)
• grub2: Heap out-of-bounds write in short form option parser (CVE-2021-20225)
• grub2: Heap out-of-bounds write due to miscalculation of space required for quoting (CVE-2021-20233)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the Red Hat Enterprise Linux 8.4 Release Notes linked from the References section.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux for x86_64 8 x86_64
• Red Hat Enterprise Linux for ARM 64 8 aarch64
• Red Hat CodeReady Linux Builder for x86_64 8 x86_64
• Red Hat CodeReady Linux Builder for ARM 64 8 aarch64

Fixes

• BZ - 1873150 - CVE-2020-14372 grub2: acpi command allows privileged user to load crafted ACPI tables when Secure Boot is enabled
• BZ - 1879577 - CVE-2020-25632 grub2: Use-after-free in rmmod command
• BZ - 1886936 - CVE-2020-25647 grub2: Out-of-bounds write in grub_usb_device_initialize()
• BZ - 1899966 - CVE-2020-27749 grub2: Stack buffer overflow in grub_parser_split_cmdline()
• BZ - 1900698 - CVE-2020-27779 grub2: cutmem command allows privileged user to remove memory regions when Secure Boot is enabled
• BZ - 1924696 - CVE-2021-20225 grub2: Heap out-of-bounds write in short form option parser
• BZ - 1926263 - CVE-2021-20233 grub2: Heap out-of-bounds write due to miscalculation of space required for quoting

CVEs

• CVE-2020-14372
• CVE-2020-25632
• CVE-2020-25647
• CVE-2020-27749
• CVE-2020-27779
• CVE-2021-20225
• CVE-2021-20233

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/security/vulnerabilities/RHSB-2021-003
• https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/8.4_release_notes/