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====================================================================                   
Red Hat Security Advisory

Synopsis:          Moderate: shim security update
Advisory ID:       RHSA-2021:1734-01
Product:           Red Hat Enterprise Linux
Advisory URL:      https://access.redhat.com/errata/RHSA-2021:1734
Issue date:        2021-05-18
CVE Names:         CVE-2020-14372 CVE-2020-25632 CVE-2020-25647
                   CVE-2020-27749 CVE-2020-27779 CVE-2021-20225
                   CVE-2021-20233
====================================================================
1. Summary:

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.

2. Relevant releases/architectures:

Red Hat CodeReady Linux Builder (v. 8) - aarch64, x86_64
Red Hat Enterprise Linux BaseOS (v. 8) - aarch64, x86_64

3. 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.

4. 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

5. Bugs fixed (https://bugzilla.redhat.com/):

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

6. Package List:

Red Hat Enterprise Linux BaseOS (v. 8):

Source:
shim-15.4-2.el8_1.src.rpm

aarch64:
shim-aa64-15.4-2.el8_1.aarch64.rpm

x86_64:
shim-ia32-15.4-2.el8_1.x86_64.rpm
shim-x64-15.4-2.el8_1.x86_64.rpm

Red Hat CodeReady Linux Builder (v. 8):

Source:
shim-unsigned-aarch64-15-7.el8_1.src.rpm
shim-unsigned-x64-15.4-4.el8_1.src.rpm

aarch64:
shim-unsigned-aarch64-15-7.el8_1.aarch64.rpm

x86_64:
shim-unsigned-x64-15.4-4.el8_1.x86_64.rpm

These packages are GPG signed by Red Hat for security.  Our key and
details on how to verify the signature are available from
https://access.redhat.com/security/team/key/

7. References:

https://access.redhat.com/security/cve/CVE-2020-14372
https://access.redhat.com/security/cve/CVE-2020-25632
https://access.redhat.com/security/cve/CVE-2020-25647
https://access.redhat.com/security/cve/CVE-2020-27749
https://access.redhat.com/security/cve/CVE-2020-27779
https://access.redhat.com/security/cve/CVE-2021-20225
https://access.redhat.com/security/cve/CVE-2021-20233
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/

8. Contact:

The Red Hat security contact is <secalert@redhat.com>. More contact
details at https://access.redhat.com/security/team/contact/

Copyright 2021 Red Hat, Inc.
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