A shim security update has been released for Fedora 34.

SECURITY: Fedora 34 Update: shim-15.4-4

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Fedora Update Notification
FEDORA-2021-cab258a413
2021-04-23 21:03:15.426820
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Name : shim
Product : Fedora 34
Version : 15.4
Release : 4
URL :   https://github.com/rhboot/shim/
Summary : First-stage UEFI bootloader
Description :
Initial UEFI bootloader that handles chaining to a trusted full bootloader
under secure boot environments. This package contains the version signed by
the UEFI signing service.

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Update Information:

- Update to shim 15.4 - Support for revocations via the ".sbat" section and
SBAT EFI variable - A new unit test framework and a bunch of unit tests - No
external gnu-efi dependency - Better CI Resolves: CVE-2020-14372 Resolves:
CVE-2020-25632 Resolves: CVE-2020-25647 Resolves: CVE-2020-27749 Resolves:
CVE-2020-27779 Resolves: CVE-2021-20225 Resolves: CVE-2021-20233 - Mark
signed shim packages as protected in dnf. Resolves: rhbz#1874541 - Conflict
with older fwupd, but don't require it. Resolves: rhbz#1877751
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ChangeLog:

* Wed Apr 21 2021 Javier Martinez Canillas - 15.4-4
- Fix handling of ignore_db and user_insecure_mode (pjones)
- Fix booting on pre-UEFI Macs (pjones)
- Fix mok variable storage allocation region (glin)
Resolves: rhbz#1948432
- Fix the package version in the .sbat data (pjones)
* Tue Apr 6 2021 Peter Jones - 15.4-3
- Mark signed shim packages as protected in dnf.
Resolves: rhbz#1874541
- Conflict with older fwupd, but don't require it.
Resolves: rhbz#1877751
* Tue Apr 6 2021 Peter Jones - 15.4-2
- Update to shim 15.4
- Support for revocations via the ".sbat" section and SBAT EFI variable
- A new unit test framework and a bunch of unit tests
- No external gnu-efi dependency
- Better CI
Resolves: CVE-2020-14372
Resolves: CVE-2020-25632
Resolves: CVE-2020-25647
Resolves: CVE-2020-27749
Resolves: CVE-2020-27779
Resolves: CVE-2021-20225
Resolves: CVE-2021-20233
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References:

[ 1 ] Bug #1592148 - pxeboot shim crash using newer edk2 firmware
  https://bugzilla.redhat.com/show_bug.cgi?id=1592148
[ 2 ] Bug #1651016 - kexec/kdump kernel fails to load with EFI secure boot enabled
  https://bugzilla.redhat.com/show_bug.cgi?id=1651016
[ 3 ] Bug #1874541 - Please mark shim packages as protected packages with DNF
  https://bugzilla.redhat.com/show_bug.cgi?id=1874541
[ 4 ] Bug #1877751 - fwupd replacing dbxtool.x86_64 8-13.fc33
  https://bugzilla.redhat.com/show_bug.cgi?id=1877751
[ 5 ] Bug #1938630 - include new bootloaders on Fedora 34 install media so UEFI Secure Boot enabled systems can boot from them
  https://bugzilla.redhat.com/show_bug.cgi?id=1938630
[ 6 ] Bug #1948432 - efi: Failed to lookup EFI memory descriptor for 0x000000003a572000
  https://bugzilla.redhat.com/show_bug.cgi?id=1948432
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This update can be installed with the "dnf" update program. Use
su -c 'dnf upgrade --advisory FEDORA-2021-cab258a413' at the command
line. For more information, refer to the dnf documentation available at
  http://dnf.readthedocs.io/en/latest/command_ref.html#upgrade-command-label

All packages are signed with the Fedora Project GPG key. More details on the
GPG keys used by the Fedora Project can be found at
  https://fedoraproject.org/keys