A grub2 security update has been released for Debian GNU/Linux 11 and 12 to address multiple vulnerabilities that may result in a Secure Boot bypass.

[SECURITY] [DSA 5519-1] grub2 security update

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Debian Security Advisory DSA-5519-1 security@debian.org
https://www.debian.org/security/ Salvatore Bonaccorso
October 06, 2023 https://www.debian.org/security/faq
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Package : grub2
CVE ID : CVE-2023-4692 CVE-2023-4693

Maxim Suhanov discovered multiple vulnerabilities in GURB2's code to
handle NTFS filesystems, which may result in a Secure Boot bypass.

For the oldstable distribution (bullseye), these problems have been fixed
in version 2.06-3~deb11u6.

For the stable distribution (bookworm), these problems have been fixed in
version 2.06-13+deb12u1.

We recommend that you upgrade your grub2 packages.

For the detailed security status of grub2 please refer to its security
tracker page at:
https://security-tracker.debian.org/tracker/grub2

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/