The grub_ext2_read_block function in fs/ext2.c in GNU GRUB before 2013-11-12, as used in shlr/grub/fs/ext2.c in radare2 1.5.0, allows remote attackers to cause a denial of service (excessive stack use and application crash) via a crafted binary file, related to use of a variable-size stack array.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - The grub_ext2_read_block function in fs/ext2.c in GNU GRUB before 2013-11-12, as used in     shlr/grub/fs/ext2.c in radare2 1.5.0, allows remote attackers to cause a denial of service (excessive     stack use and application crash) via a crafted binary file, related to use of a variable-size stack array.
    (CVE-2017-9763)

Note that Nessus relies on the presence of the package as reported by the vendor.

The remote SUSE Linux SLES11 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2021:14659-1 advisory.

  - The grub_ext2_read_block function in fs/ext2.c in GNU GRUB before 2013-11-12, as used in     shlr/grub/fs/ext2.c in radare2 1.5.0, allows remote attackers to cause a denial of service (excessive     stack use and application crash) via a crafted binary file, related to use of a variable-size stack array.
    (CVE-2017-9763)

  - 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 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 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)

  - 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)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

This update for grub2 fixes the following issues :

Security issue fixed :

CVE-2017-9763: Fixed a memory leak in grub_ext2_read_block (bsc#1045063)

Other issues addressed: Added support for tftp block counter roll-over and backported support for efinetSNP open (bsc#1124662).

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Type	Severity
253937	Linux Distros Unpatched Vulnerability : CVE-2017-9763	Nessus	Misc.	Local	high
150532	SUSE SLES11 Security Update : grub2 (SUSE-SU-2021:14659-1)	Nessus	SuSE Local Security Checks	Local	high
123452	SUSE SLES11 Security Update : grub2 (SUSE-SU-2019:13989-1)	Nessus	SuSE Local Security Checks	Local	high

Detections

Analytics

CVE-2017-9763

high

Tenable Plugins

high

high

high