Important: grub2, mokutil, shim, and shim-unsigned-x64 security update

Topic

An update for grub2, mokutil, shim, and shim-unsigned-x64 is now available for Red Hat Enterprise Linux 9.

Red Hat Product Security has rated this update as having a security impact of Important. 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 grub2 packages provide version 2 of the Grand Unified Boot Loader (GRUB), a highly configurable and customizable boot loader with modular architecture. The packages support a variety of kernel formats, file systems, computer architectures, and hardware devices.

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: Integer underflow in grub_net_recv_ip4_packets (CVE-2022-28733)
• grub2: Crafted PNG grayscale images may lead to out-of-bounds write in heap (CVE-2021-3695)
• grub2: Crafted PNG image may lead to out-of-bound write during huffman table handling (CVE-2021-3696)
• grub2: Crafted JPEG image can lead to buffer underflow write in the heap (CVE-2021-3697)
• grub2: Out-of-bound write when handling split HTTP headers (CVE-2022-28734)
• grub2: shim_lock verifier allows non-kernel files to be loaded (CVE-2022-28735)
• grub2: use-after-free in grub_cmd_chainloader() (CVE-2022-28736)
• shim: Buffer overflow when loading crafted EFI images (CVE-2022-28737)

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.

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 9 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 9.0 x86_64
• Red Hat Enterprise Linux for Power, little endian 9 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.0 ppc64le
• Red Hat Enterprise Linux for ARM 64 9 aarch64
• Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.0 aarch64
• Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.0 ppc64le
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.0 x86_64
• Red Hat CodeReady Linux Builder for x86_64 9 x86_64
• Red Hat CodeReady Linux Builder for x86_64 - Extended Update Support 9.0 x86_64
• Red Hat Enterprise Linux Server for ARM 64 - 4 years of updates 9.0 aarch64

Fixes

• BZ - 1991685 - CVE-2021-3695 grub2: Crafted PNG grayscale images may lead to out-of-bounds write in heap
• BZ - 1991686 - CVE-2021-3696 grub2: Crafted PNG image may lead to out-of-bound write during huffman table handling
• BZ - 1991687 - CVE-2021-3697 grub2: Crafted JPEG image can lead to buffer underflow write in the heap
• BZ - 2083339 - CVE-2022-28733 grub2: Integer underflow in grub_net_recv_ip4_packets
• BZ - 2090463 - CVE-2022-28734 grub2: Out-of-bound write when handling split HTTP headers
• BZ - 2090857 - CVE-2022-28735 grub2: shim_lock verifier allows non-kernel files to be loaded
• BZ - 2090899 - CVE-2022-28737 shim: Buffer overflow when loading crafted EFI images
• BZ - 2092613 - CVE-2022-28736 grub2: use-after-free in grub_cmd_chainloader()

CVEs

• CVE-2021-3695
• CVE-2021-3696
• CVE-2021-3697
• CVE-2022-28733
• CVE-2022-28734
• CVE-2022-28735
• CVE-2022-28736
• CVE-2022-28737

References

• https://access.redhat.com/security/updates/classification/#important