Affected: grub2

When rendering certain unicode sequences, grub2's font code doesn't proper validate if the informed glyph's width and height is constrained within bitmap size. As consequence an attacker can craft an input which will lead to a out-of-bounds write into grub2's heap, leading to memory corruption and availability issues. Although complex, arbitrary code execution could not be discarded.

Affected: Ubuntu:20.04:LTS: grub2-signed, Ubuntu:20.04:LTS: grub2-unsigned, Ubuntu:20.04:LTS: shim, Ubuntu:20.04:LTS: shim-signed, Ubuntu:22.04:LTS: grub2-signed, Ubuntu:22.04:LTS: grub2-unsigned, Ubuntu:22.04:LTS: shim, Ubuntu:22.04:LTS: shim-signed

Daniel Axtens discovered that specially crafted images could cause a heap-based out-of-bonds write. A local attacker could possibly use this to circumvent secure boot protections. (CVE-2021-3695)

Daniel Axtens discovered that specially crafted images could cause out-of-bonds read and write. A local attacker could possibly use this to circumvent secure boot protections. (CVE-2021-3696)

Daniel Axtens discovered that specially crafted images could cause buffer underwrite which allows arbitrary data to be written to a heap. A local attacker could possibly use this to circumvent secure boot protections. (CVE-2021-3697)

It was discovered that GRUB2 configuration files were created with the wrong permissions. An attacker could possibly use this to leak encrypted passwords. (CVE-2021-3981)

Daniel Axtens discovered that specially crafted IP packets could cause an integer underflow and write past the end of a buffer. An attacker could possibly use this to circumvent secure boot protections. (CVE-2022-28733)

Daniel Axtens discovered that specially crafted HTTP headers can cause an out-of-bounds write of a NULL byte. An attacker could possibly use this to corrupt GRUB2's internal data. (CVE-2022-28734)

Julian Andres Klode discovered that GRUB2 shim_lock allowed non- kernel files to be loaded. A local attack could possibly use this to circumvent secure boot protections. (CVE-2022-28735)

Chris Coulson discovered that executing chainloaders more than once caused a use-after-free vul…