Topic

An update for grub2, shim, shim-signed, and fwupdate is now available for Red Hat Enterprise Linux 7.

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.

[Updated 3 August 2020]

The shim and shim-signed packages distributed with this erratum have a known bug that can cause the boot process to hang on some systems. To prevent boot problems, customers are strongly recommended not to use the shim packages released with this erratum, and instead to apply the newer packages within RHBA-2020:3265, that were released on 1 August 2020 to address this issue.

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.

The fwupdate packages provide a service that allows session software to update device firmware.

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)
• grub2: Integer overflow in initrd size handling (CVE-2020-15707)

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 doesn't handle relative paths correctly for UEFI HTTP Boot (BZ#1616395)
• UEFI HTTP boot over IPv6 does not work (BZ#1732765)

Users of grub2 are advised to upgrade to these updated packages, which fix these bugs.

Solution

Before applying this update, make sure all previously released errata relevant to your system have been applied.

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 7 x86_64
• Red Hat Enterprise Linux Workstation 7 x86_64
• Red Hat Enterprise Linux Desktop 7 x86_64
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux for Power, little endian 7 ppc64le

Fixes

• BZ - 1616395 - grub2 doesn't handle relative paths correctly for UEFI HTTP Boot
• BZ - 1732765 - UEFI HTTP boot over IPv6 does not work
• 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 - 1861581 - CVE-2020-15707 grub2: Integer overflow in initrd size handling

CVEs

• CVE-2020-10713
• CVE-2020-14308
• CVE-2020-14309
• CVE-2020-14310
• CVE-2020-14311
• CVE-2020-15705
• CVE-2020-15706
• CVE-2020-15707

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/security/vulnerabilities/grub2bootloader
• https://access.redhat.com/errata/RHBA-2020:3265