CVE-2020-27749

A flaw was found in grub2 in versions prior to 2.06. Variable names present are expanded in the supplied command line into their corresponding variable contents, using a 1kB stack buffer for temporary storage, without sufficient bounds checking. If the function is called with a command line that references a variable with a sufficiently large payload, it is possible to overflow the stack buffer, corrupt the stack frame and control execution which could also circumvent Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

A flaw was found in grub2 in versions prior to 2.06. Variable names present are expanded in the supplied command line into their corresponding variable contents, using a 1kB stack buffer for temporary storage, without sufficient bounds checking. If the function is called with a command line that references a variable with a sufficiently large payload, it is possible to overflow the stack buffer, corrupt the stack frame and control execution which could also circumvent Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

GNU GRUB is a Multiboot boot loader. It was derived from GRUB, the GRand Unified Bootloader, which was originally designed and implemented by Erich Stefan Boleyn. Briefly, a boot loader is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the operating system kernel software (such as the Hurd or Linux). The kernel, in turn, initializes the rest of the operating system (e.g. GNU).

Security Fix(es):

A flaw was found in grub2 in versions prior to 2.06. The rmmod implementation allows the unloading of a module used as a dependency without checking if any other dependent module is still loaded leading to a use-after-free scenario. This could allow arbitrary code to be executed or a bypass of Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.(CVE-2020-25632)

A flaw was found in grub2 in versions prior to 2.06. During USB device initialization, descriptors are read with very little bounds checking and assumes the USB device is providing sane values. If properly exploited, an attacker could trigger memory corruption leading to arbitrary code execution allowing a bypass of the Secure Boot mechanism. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.(CVE-2020-25647)

A flaw was found in grub2 in versions prior to 2.06. Variable names present are expanded in the supplied command line into their corresponding variable contents, using a 1kB stack buffer for temporary storage, without sufficient bounds checking. If the function is called with a command line that references a variable with a sufficiently large payload, it is possible to overflow the stack buffer, corrupt the stack frame and control execution which could also circumvent Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.(CVE-2020-27749)

A flaw was found in grub2 in versions prior to 2.06. The option parser allows an attacker to write past the end of a heap-allocated buffer by calling certain commands with a large number of specific short forms of options. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.(CVE-2021-20225)

A flaw was found in grub2 in versions prior to 2.06. Setparam_prefix() in the menu rendering code performs a length calculation on the assumption that expressing a quoted single quote will require 3 characters, while it actually requires 4 characters which allows an attacker to corrupt memory by one byte for each quote in the input. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.(CVE-2021-20233)

A flaw was found in grub2 in versions prior to 2.06, where it incorrectly enables the usage of the ACPI command when Secure Boot is enabled. This flaw allows an attacker with privileged access to craft a Secondary System Description Table (SSDT) containing code to overwrite the Linux kernel lockdown variable content directly into memory. The table is further loaded and executed by the kernel, defeating its Secure Boot lockdown and allowing the attacker to load unsigned code. The highest threat from this vulnerability is to data confidentiality and integrity, as well as system availability.(CVE-2020-14372)

A flaw was found in grub2 in versions prior to 2.06. The cutmem command does not honor secure boot locking allowing an privileged attacker to remove address ranges from memory creating an opportunity to circumvent SecureBoot protections after proper triage about grub's memory layout. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.(CVE-2020-27779)

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 Rocky Linux 8.4 Release Notes linked from the References section.

The fwupd packages provide a service that allows session software to update device firmware.

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.

A flaw was found in grub2 in versions prior to 2.06. Variable names present are expanded in the supplied command line into their corresponding variable contents, using a 1kB stack buffer for temporary storage, without sufficient bounds checking. If the function is called with a command line that references a variable with a sufficiently large payload, it is possible to overflow the stack buffer, corrupt the stack frame and control execution which could also circumvent Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

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 AlmaLinux Release Notes linked from the References section.

All CVEs below are against the SecureBoot functionality in GRUB2. We do not ship this as part of Mageia. Therefore, we ship an updated grub2 package to 2.06 for Mageia 8 fixing upstream bugfixes.

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 (CVE-2020-10713).

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 (CVE-2020-14308).

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 (CVE-2020-14309).

There is an issue on grub2 before version 2.06 at function read_section_as_string(). It expects a font name to be at max UINT32_MAX - 1 length in bytes but it doesn't verify it before proceed with buffer allocation to read the value from the font value. An attacker may leverage that by crafting a malicious font file which has a name with UINT32_MAX, leading to read_section_as_string() to an arithmetic overflow, zero-sized allocation and further heap-based buffer overflow (CVE-2020-14310).

There is an issue with grub2 before version 2.06 while handling symlink on ext filesystems. A filesystem containing a symbolic link with an inode size of UINT32_MAX causes an arithmetic overflow leading to a zero-sized memory allocation with subsequent heap-based buffer overflow (CVE-2020-14311).

A flaw was found in grub2 in versions prior to 2.06, where it incorrectly enables the usage of the ACPI command when Secure Boot is enabled. This flaw allows an attacker with privileged access to craft a Secondary System Description Table (SSDT) containing code to overwrite the Linux kernel lockdown variable content directly into memory. The table is further loaded and executed by the kernel, defeating its Secure Boot lockdown and allowing the attacker to load unsigned code. The highest threat from this vulnerability is to data confidentiality and integrity, as well as system availability (CVE-2020-14372).

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. This issue affects GRUB2 version 2.04 and prior versions (CVE-2020-15705).

GRUB2 contains a race condition in grub_script_function_create() 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 version 2.04 and prior versions (CVE-2020-15706).

Integer overflows were discovered in the functions grub_cmd_initrd and grub_initrd_init 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…

This update for grub2 fixes the following issues:

grub2 implements the new 'SBAT' method for SHIM based secure boot revocation. (bsc#1182057)

• CVE-2020-25632: Fixed a use-after-free in rmmod command (bsc#1176711)

• CVE-2020-25647: Fixed an out-of-bound write in grub_usb_device_initialize() (bsc#1177883)

• CVE-2020-27749: Fixed a stack buffer overflow in grub_parser_split_cmdline (bsc#1179264)

• CVE-2020-27779, CVE-2020-14372: Disallow cutmem and acpi commands in secure boot mode (bsc#1179265 bsc#1175970)

• CVE-2021-20225: Fixed a heap out-of-bounds write in short form option parser (bsc#1182262)

• CVE-2021-20233: Fixed a heap out-of-bound write due to mis-calculation of space required for quoting (bsc#1182263)

• Fixed chainloading windows on dual boot machine (bsc#1183073)

This update was imported from the SUSE:SLE-15-SP2:Update update project.

These are all security issues fixed in the grub2-2.06-7.1 package on the GA media of openSUSE Tumbleweed.

This update for grub2 fixes the following issues:

grub2 now implements the new 'SBAT' method for SHIM based secure boot revocation. (bsc#1182057)

Following security issues are fixed that can violate secure boot constraints:

• CVE-2020-25632: Fixed a use-after-free in rmmod command (bsc#1176711)
• CVE-2020-25647: Fixed an out-of-bound write in grub_usb_device_initialize() (bsc#1177883)
• CVE-2020-27749: Fixed a stack buffer overflow in grub_parser_split_cmdline (bsc#1179264)
• CVE-2020-27779, CVE-2020-14372: Disallow cutmem and acpi commands in secure boot mode (bsc#1179265 bsc#1175970)
• CVE-2021-20225: Fixed a heap out-of-bounds write in short form option parser (bsc#1182262)
• CVE-2021-20233: Fixed a heap out-of-bound write due to mis-calculation of space required for quoting (bsc#1182263)

grub2 was bumped to version 2.02, same as SUSE Linux Enterprise 12 SP3.

This update for grub2 fixes the following issues:

grub2 now implements the new 'SBAT' method for SHIM based secure boot revocation. (bsc#1182057)

Following security issues are fixed that can violate secure boot constraints:

• CVE-2020-25632: Fixed a use-after-free in rmmod command (bsc#1176711)
• CVE-2020-25647: Fixed an out-of-bound write in grub_usb_device_initialize() (bsc#1177883)
• CVE-2020-27749: Fixed a stack buffer overflow in grub_parser_split_cmdline (bsc#1179264)
• CVE-2020-27779, CVE-2020-14372: Disallow cutmem and acpi commands in secure boot mode (bsc#1179265 bsc#1175970)
• CVE-2021-20225: Fixed a heap out-of-bounds write in short form option parser (bsc#1182262)
• CVE-2021-20233: Fixed a heap out-of-bound write due to mis-calculation of space required for quoting (bsc#1182263)

This update for grub2 fixes the following issues:

grub2 now implements the new 'SBAT' method for SHIM based secure boot revocation. (bsc#1182057)

Following security issues are fixed that can violate secure boot constraints:

• CVE-2020-25632: Fixed a use-after-free in rmmod command (bsc#1176711)
• CVE-2020-25647: Fixed an out-of-bound write in grub_usb_device_initialize() (bsc#1177883)
• CVE-2020-27749: Fixed a stack buffer overflow in grub_parser_split_cmdline (bsc#1179264)
• CVE-2020-27779, CVE-2020-14372: Disallow cutmem and acpi commands in secure boot mode (bsc#1179265 bsc#1175970)
• CVE-2021-20225: Fixed a heap out-of-bounds write in short form option parser (bsc#1182262)
• CVE-2021-20233: Fixed a heap out-of-bound write due to mis-calculation of space required for quoting (bsc#1182263)

This update for grub2 fixes the following issues:

grub2 implements the new 'SBAT' method for SHIM based secure boot revocation. (bsc#1182057)

• CVE-2020-25632: Fixed a use-after-free in rmmod command (bsc#1176711)
• CVE-2020-25647: Fixed an out-of-bound write in grub_usb_device_initialize() (bsc#1177883)
• CVE-2020-27749: Fixed a stack buffer overflow in grub_parser_split_cmdline (bsc#1179264)
• CVE-2020-27779, CVE-2020-14372: Disallow cutmem and acpi commands in secure boot mode (bsc#1179265 bsc#1175970)
• CVE-2021-20225: Fixed a heap out-of-bounds write in short form option parser (bsc#1182262)
• CVE-2021-20233: Fixed a heap out-of-bound write due to mis-calculation of space required for quoting (bsc#1182263)

This update for grub2 fixes the following issues:

grub2 now implements the new 'SBAT' method for SHIM based secure boot revocation. (bsc#1182057)

Following security issues are fixed that can violate secure boot constraints:

• CVE-2020-25632: Fixed a use-after-free in rmmod command (bsc#1176711)
• CVE-2020-25647: Fixed an out-of-bound write in grub_usb_device_initialize() (bsc#1177883)
• CVE-2020-27749: Fixed a stack buffer overflow in grub_parser_split_cmdline (bsc#1179264)
• CVE-2020-27779, CVE-2020-14372: Disallow cutmem and acpi commands in secure boot mode (bsc#1179265 bsc#1175970)
• CVE-2021-20225: Fixed a heap out-of-bounds write in short form option parser (bsc#1182262)
• CVE-2021-20233: Fixed a heap out-of-bound write due to mis-calculation of space required for quoting (bsc#1182263)

This update for grub2 fixes the following issues:

grub2 now implements the new 'SBAT' method for SHIM based secure boot revocation. (bsc#1182057)

Following security issues are fixed that can violate secure boot constraints:

• CVE-2020-25632: Fixed a use-after-free in rmmod command (bsc#1176711)
• CVE-2020-25647: Fixed an out-of-bound write in grub_usb_device_initialize() (bsc#1177883)
• CVE-2020-27749: Fixed a stack buffer overflow in grub_parser_split_cmdline (bsc#1179264)
• CVE-2020-27779, CVE-2020-14372: Disallow cutmem and acpi commands in secure boot mode (bsc#1179265 bsc#1175970)
• CVE-2021-20225: Fixed a heap out-of-bounds write in short form option parser (bsc#1182262)
• CVE-2021-20233: Fixed a heap out-of-bound write due to mis-calculation of space required for quoting (bsc#1182263)

This update for grub2 fixes the following issues:

grub2 now implements the new 'SBAT' method for SHIM based secure boot revocation. (bsc#1182057)

grub2 was updated to the 2.02 version (same as SUSE Linux Enterprise 12 SP3).

Following security issues are fixed that can violate secure boot constraints:

• CVE-2020-25632: Fixed a use-after-free in rmmod command (bsc#1176711)
• CVE-2020-25647: Fixed an out-of-bound write in grub_usb_device_initialize() (bsc#1177883)
• CVE-2020-27749: Fixed a stack buffer overflow in grub_parser_split_cmdline (bsc#1179264)
• CVE-2020-27779, CVE-2020-14372: Disallow cutmem and acpi commands in secure boot mode (bsc#1179265 bsc#1175970)
• CVE-2021-20225: Fixed a heap out-of-bounds write in short form option parser (bsc#1182262)
• CVE-2021-20233: Fixed a heap out-of-bound write due to mis-calculation of space required for quoting (bsc#1182263)

Máté Kukri discovered that the acpi command in GRUB 2 allowed privileged users to load crafted ACPI tables when secure boot is enabled. An attacker could use this to bypass UEFI Secure Boot restrictions. (CVE-2020-14372)

Chris Coulson discovered that the rmmod command in GRUB 2 contained a use- after-free vulnerability. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-25632)

Chris Coulson discovered that a buffer overflow existed in the command line parser in GRUB 2. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-27749)

It was discovered that the cutmem command in GRUB 2 did not honor secure boot locking. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-27779)

It was discovered that the option parser in GRUB 2 contained a heap overflow vulnerability. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2021-20225)

It was discovered that the menu rendering implementation in GRUB 2 did not properly calculate the amount of memory needed in some situations, leading to out-of-bounds writes. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2021-20233)