The vulnerability of Grub2 operating system loaders, related to integer overflows in value handling, allows attackers to access confidential data, compromise its integrity, and cause service failures.

The vulnerability of the Grub2 operating system loader is related to a numerical overflow of the UINT32 value. Exploiting this vulnerability can allow an attacker to access confidential data, compromise its integrity, and cause service failures...

There's an issue with grub2 in all versions before 2.06 when handling squashfs filesystems containing a symbolic link with name length of UINT32 bytes in size. The name size leads to an arithmetic overflow leading to a zero-size allocation further causing a heap-based buffer overflow with attacker controlled data.

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GRUB2 contained integer overflows when handling the initrd command leading to a heap-based buffer overflow.

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GRUB2: avoid loading unsigned kernels when GRUB is booted directly under secureboot without shim

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A flaw was found in grub2 prior to version 2.06. An attacker may use the GRUB 2 flaw to hijack and tamper the GRUB verification process. This flaw also allows the bypass of Secure Boot protections. In order to load an untrusted or modified kernel an attacker would first need to establish access to the system such as gaining physical access obtain the ability to alter a pxe-boot network or have remote access to a networked system with root access. With this access an attacker could then craft a string to cause a buffer overflow by injecting a malicious payload that leads to arbitrary code execution within GRUB. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

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GRUB2 contains a race condition leading to a use-after-free vulnerability which can be triggered by redefining a function whilst the same function is already executing.

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In grub2 versions before 2.06 the grub memory allocator doesn't check for possible arithmetic overflows on the requested allocation size. This leads the function to return invalid memory allocations which can be further used to cause possible integrity confidentiality and availability impacts during the boot process.

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Multiple integer underflows in Grub2 1.98 through 2.02 allow physically proximate attackers to bypass authentication obtain sensitive information or cause a denial of service (disk corruption) via backspace characters in the (1) grub_username_get function in grub-core/normal/auth.c or the (2) grub_password_get function in lib/crypto.c which trigger an "Off-by-two" or "Out of bounds overwrite" memory error.

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USN-4432-2 grub2, grub2-signed regression

USN-4432-1 fixed vulnerabilities in GRUB2 affecting Secure Boot environments. Unfortunately, the update introduced regressions for some BIOS systems either pre-UEFI or UEFI configured in Legacy mode, preventing them from successfully booting. This update addresses the issue. Users with BIOS syste...

Vulnerabilities fixed in GRUB2

Researchers have found multiple vulnerabilities in GRUB2. The vulnerability with reference CVE-2020-10713 has been named "Boothole." assigned. This vulnerability allows a malicious person with physical access to the system or a malicious person with administrator privileges able to execute...

grub2: Integer overflow read_section_as_string may lead to heap-based buffer overflow

A flaw was found in grub2. An expected font value is not verified before proceeding with buffer allocations allowing an attacker to use a malicious font file to create an arithmetic overflow, zero-sized allocation, and further heap-based buffer overflow. The highest threat from this vulnerability...

grub2: Integer overflow in initrd size handling

Integer overflows were discovered in the functions grubcmdinitrd and grubinitrdinit in the efilinux component of GRUB2, as shipped in Debian, Red Hat, and Ubuntu the functionality is not included in GRUB2 upstream, leading to a heap-based buffer overflow. These could be triggered by an extremely...

grub2: grub_malloc does not validate allocation size allowing for arithmetic overflow and subsequent heap-based buffer overflow

A flaw was found in current grub2 versions as shipped with Red Hat Enterprise Linux 7 and 8, where the grub memory allocator doesn't check for possible arithmetic overflows on the requested allocation size. This issue leads the function to return invalid memory allocations, causing heap-based...

grub2: Integer overflow in grub_ext2_read_link leads to heap-based buffer overflow

A flaw was found in grub2 while handling symlink on ext filesystems. A filesystem containing a symbolic link with an inode size of UINT32MAX causes an arithmetic overflow, leading to a zero-sized memory allocation with a subsequent heap-based buffer overflow. The highest threat from this...

grub2: Use-after-free redefining a function whilst the same function is already executing

GRUB2 contains a race condition in grubscriptfunctioncreate leading to a use-after-free vulnerability which can be triggered by redefining a function whilst the same function is already executing, leading to arbitrary code execution and secure boot restriction bypass. This issue affects GRUB2...

grub2: Fail kernel validation without shim protocol

GRUB2 fails to validate kernel signature when booted directly without shim, allowing secure boot to be bypassed. This only affects systems where the kernel signing certificate has been imported directly into the secure boot database and the GRUB image is booted directly without the use of shim...

grub2: Integer overflow read_section_as_string may lead to heap-based buffer overflow

A flaw was found in grub2. An expected font value is not verified before proceeding with buffer allocations allowing an attacker to use a malicious font file to create an arithmetic overflow, zero-sized allocation, and further heap-based buffer overflow. The highest threat from this vulnerability...

grub2: Fail kernel validation without shim protocol

GRUB2 fails to validate kernel signature when booted directly without shim, allowing secure boot to be bypassed. This only affects systems where the kernel signing certificate has been imported directly into the secure boot database and the GRUB image is booted directly without the use of shim...

grub2: Integer overflow in initrd size handling

Integer overflows were discovered in the functions grubcmdinitrd and grubinitrdinit in the efilinux component of GRUB2, as shipped in Debian, Red Hat, and Ubuntu the functionality is not included in GRUB2 upstream, leading to a heap-based buffer overflow. These could be triggered by an extremely...

grub2: Integer overflow in grub_squash_read_symlink may lead to heap-based buffer overflow

A flaw was found in grub2. When handling squashfs filesystems containing a symbolic link with name length of UINT32 bytes in size, the name size leads to an arithmetic overflow leading to a zero-size allocation further causing a heap-based buffer overflow with attacker controlled data. The highes...