A flaw was found in grub2. When performing a symlink lookup from a romfs filesystem, grub's romfs filesystem module uses user-controlled parameters from the filesystem geometry to determine the internal buffer size, however, it improperly checks for integer overflows. A maliciously crafted filesystem may lead some of those buffer size calculations to overflow, causing it to perform a grub_malloc() operation with a smaller size than expected. As a result, the grub_romfs_read_symlink() may cause out-of-bounds writes when the calling grub_disk_read() function. This issue may be leveraged to corrupt grub's internal critical data and can result in arbitrary code execution by-passing secure boot protections.

The read command is used to read the keyboard input from the user, while reads it keeps the input length in a 32-bit integer value which is further used to reallocate the line buffer to accept the next character. During this process, with a line big enough it's possible to make this variable to overflow leading to a out-of-bounds write in the heap based buffer. This flaw may be leveraged to corrupt grub's internal critical data and secure boot bypass is not discarded as consequence.

A flaw was found in grub2. The calculation of the translation buffer when reading a language .mo file in grub_gettext_getstr_from_position() may overflow, leading to a Out-of-bound write. This issue can be leveraged by an attacker to overwrite grub2's sensitive heap data, eventually leading to the circumvention of secure boot protections.

A flaw was found in grub2. Grub's dump command is not blocked when grub is in lockdown mode, which allows the user to read any memory information, and an attacker may leverage this in order to extract signatures, salts, and other sensitive information from the memory.

A flaw was found in grub2. When performing a symlink lookup, the grub's UFS module checks the inode's data size to allocate the internal buffer to read the file content, however, it fails to check if the symlink data size has overflown. When this occurs, grub_malloc() may be called with a smaller value than needed. When further reading the data from the disk into the buffer, the grub_ufs_lookup_symlink() function will write past the end of the allocated size. An attack can leverage this by crafting a malicious filesystem, and as a result, it will corrupt data stored in the heap, allowing for arbitrary code execution used to by-pass secure boot mechanisms.

A flaw was found in grub2. During the network boot process, when trying to search for the configuration file, grub copies data from a user controlled environment variable into an internal buffer using the grub_strcpy() function. During this step, it fails to consider the environment variable length when allocating the internal buffer, resulting in an out-of-bounds write. If correctly exploited, this issue may result in remote code execution through the same network segment grub is searching for the boot information, which can be used to by-pass secure boot protections.

A flaw was found in grub2. When reading a symbolic link's name from a UFS filesystem, grub2 fails to validate the string length taken as an input. The lack of validation may lead to a heap out-of-bounds write, causing data integrity issues and eventually allowing an attacker to circumvent secure boot protections.

A flaw was found in grub2. When failing to mount an HFS+ grub, the hfsplus filesystem driver doesn't properly set an ERRNO value. This issue may lead to a NULL pointer access.

A flaw was found in grub2. A specially crafted JPEG file can cause the JPEG parser of grub2 to incorrectly check the bounds of its internal buffers, resulting in an out-of-bounds write. The possibility of overwriting sensitive information to bypass secure boot protections is not discarded.

A flaw was found in command/gpg. In some scenarios, hooks created by loaded modules are not removed when the related module is unloaded. This flaw allows an attacker to force grub2 to call the hooks once the module that registered it was unloaded, leading to a use-after-free vulnerability. If correctly exploited, this vulnerability may result in arbitrary code execution, eventually allowing the attacker to bypass secure boot protections.