RHSA-2020:3273 - Security Advisory

Topic

An update for grub2, shim, and shim-signed is now available for Red Hat Enterprise Linux 7.2 Advanced Update Support.

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 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: Crafted grub.cfg file can lead to arbitrary code execution during boot process (CVE-2020-10713)
• grub2: grub_malloc does not validate allocation size allowing for arithmetic overflow and subsequent heap-based buffer overflow (CVE-2020-14308)
• grub2: Integer overflow in grub_squash_read_symlink may lead to heap-based buffer overflow (CVE-2020-14309)
• grub2: Integer overflow read_section_as_string may lead to heap-based buffer overflow (CVE-2020-14310)
• grub2: Integer overflow in grub_ext2_read_link leads to heap-based buffer overflow (CVE-2020-14311)
• grub2: Fail kernel validation without shim protocol (CVE-2020-15705)
• grub2: Use-after-free redefining a function whilst the same function is already executing (CVE-2020-15706)

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.

Bug Fix(es):

• grub2 should get resynced with 7.8 branch (BZ#1861861)

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 Server - AUS 7.2 x86_64

Fixes

• BZ - 1825243 - CVE-2020-10713 grub2: Crafted grub.cfg file can lead to arbitrary code execution during boot process
• BZ - 1852009 - CVE-2020-14308 grub2: grub_malloc does not validate allocation size allowing for arithmetic overflow and subsequent heap-based buffer overflow
• BZ - 1852014 - CVE-2020-14311 grub2: Integer overflow in grub_ext2_read_link leads to heap-based buffer overflow
• BZ - 1852022 - CVE-2020-14309 grub2: Integer overflow in grub_squash_read_symlink may lead to heap-based buffer overflow
• BZ - 1852030 - CVE-2020-14310 grub2: Integer overflow read_section_as_string may lead to heap-based buffer overflow
• BZ - 1860978 - CVE-2020-15705 grub2: Fail kernel validation without shim protocol
• BZ - 1861118 - CVE-2020-15706 grub2: Use-after-free redefining a function whilst the same function is already executing
• BZ - 1861861 - grub2 should get resynced with 7.8 branch

CVEs

• CVE-2020-10713
• CVE-2020-14308
• CVE-2020-14309
• CVE-2020-14310
• CVE-2020-14311
• CVE-2020-15705
• CVE-2020-15706

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/security/vulnerabilities/grub2bootloader