The remote Redhat Enterprise Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2021:0704 advisory.

    The grub2 packages provide version 2 of the Grand Unified Boot Loader (GRUB), a highly configurable and     customizable boot loader with modular architecture. The packages support a variety of kernel formats, file     systems, computer architectures, and hardware devices.

    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.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

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

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2021:0696 advisory.

    The grub2 packages provide version 2 of the Grand Unified Boot Loader (GRUB), a highly configurable and     customizable boot loader with modular architecture. The packages support a variety of kernel formats, file     systems, computer architectures, and hardware devices.

    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.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

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

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-based 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)

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.

The remote Oracle Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2021-9077 advisory.

    - Fix CVE-2020-14372 CVE-2020-25632 CVE-2020-25647 CVE-2020-27749       CVE-2020-27779 CVE-2021-20225 CVE-2021-20233 [Orabug: 32530657]

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

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

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-based 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.

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

  - 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)

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

The remote host is affected by the vulnerability described in GLSA-202104-05 (GRUB: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in GRUB. Please review the       CVE identifiers referenced below for details.
  Impact :

    Please review the referenced CVE identifiers for details.
  Workaround :

    There is no known workaround at this time.

The remote Windows host is missing an update to the Secure Boot DBX. It is, therefore, affected by multiple vulnerabilities:

  - 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. 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)


Additionally, the host is affected by several other security feature bypasses in Secure Boot.

Note: Tenable is testing for the presence of the expected signatures added in the DBX update published on March 2, 2021 referenced in the vendor advisory.

The remote Alibaba Cloud Linux 3 host has packages installed that are affected by multiple vulnerabilities as referenced in the ALINUX3-SA-2021:0026 advisory.

    Package updates are available for Alibaba Cloud Linux 3 that fix the following vulnerabilities:

    CVE-2019-14865:
    A flaw was found in the grub2-set-bootflag utility of grub2. A local attacker could run this utility under     resource pressure (for example by setting RLIMIT), causing grub2 configuration files to be truncated and     leaving the system unbootable on subsequent reboots.

    CVE-2020-10713:
    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-2020-14308:
    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-2020-14309:
    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-2020-14310:
    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-2020-14311:
    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-2020-14372:
    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-2020-15705:
    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-2020-25632:
    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-2020-25647:
    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-2020-27749:
    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.

    CVE-2020-27779:
    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-2021-20225:
    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-2021-20233:
    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.

Tenable has extracted the preceding description block directly from the Alibaba Cloud Linux security advisory.

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

The remote CentOS Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the CESA-2021:0696 advisory.

  - 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)

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

The remote AlmaLinux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ALSA-2021:0696 advisory.

  - 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.

An update of the grub2 package has been released.

ID	Name	Product	Family	Published	Updated	Severity
146952	RHEL 7 : grub2 (RHSA-2021:0704)	Nessus	Red Hat Local Security Checks	3/2/2021	11/7/2024	high
146955	RHEL 8 : grub2 (RHSA-2021:0696)	Nessus	Red Hat Local Security Checks	3/2/2021	11/7/2024	high
146976	SUSE SLES12 Security Update : grub2 (SUSE-SU-2021:0682-1)	Nessus	SuSE Local Security Checks	3/3/2021	1/18/2024	high
146978	SUSE SLES15 Security Update : grub2 (SUSE-SU-2021:0684-1)	Nessus	SuSE Local Security Checks	3/3/2021	1/18/2024	high
146988	Oracle Linux 8 : grub2 (ELSA-2021-9077)	Nessus	Oracle Linux Local Security Checks	3/3/2021	11/2/2024	high
148045	openSUSE Security Update : grub2 (openSUSE-2021-462)	Nessus	SuSE Local Security Checks	3/24/2021	1/8/2024	high
229880	Linux Distros Unpatched Vulnerability : CVE-2020-25632	Nessus	Misc.	3/5/2025	4/28/2025	high
149217	GLSA-202104-05 : GRUB: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	5/3/2021	1/12/2024	high
139239	Windows Security Feature Bypass in Secure Boot (BootHole)	Nessus	Windows	7/31/2020	7/21/2025	high
236631	Alibaba Cloud Linux 3 : 0026: grub2 (ALINUX3-SA-2021:0026)	Nessus	Alibaba Cloud Linux Local Security Checks	5/14/2025	5/15/2025	high
146965	CentOS 8 : grub2 (CESA-2021:0696)	Nessus	CentOS Local Security Checks	3/3/2021	1/18/2024	high
157607	AlmaLinux 8 : grub2 (ALSA-2021:0696)	Nessus	Alma Linux Local Security Checks	2/9/2022	11/10/2023	high
148024	Photon OS 4.0: Grub2 PHSA-2021-4.0-0001	Nessus	PhotonOS Local Security Checks	3/24/2021	8/22/2025	high

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