There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

  - 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, 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)

远程 Windows 主机缺少安全启动 DBX 的更新。因此，该应用程序受到多个漏洞的影响：

  - 发现版本低于 2.06 的 grub2 中存在一个缺陷。rmmod 实现可卸载用作依赖项的模块，但不检查是否仍加载了任何其他依赖项模块，从而造成释放后使用情形。攻击者可利用此漏洞，执行任意代码或绕过安全启动保护。此漏洞最大的威胁在于数据机密性和完整性，以及系统可用性。
    (CVE-2020-25632)

  - 发现版本低于 2.06 的 grub2 中存在一个缺陷。菜单渲染代码中的 Setparam_prefix() 执行长度计算的前提是，表达引用的单引号需要 3 个字符，但实际需要 4 个字符，攻击者可利用此漏洞，通过每次引用时在输入中损坏一个字节来损坏内存。此漏洞最大的威胁在于数据机密性和完整性，以及系统可用性。(CVE-2021-20233)


此外，主机还受到安全启动中多个其他安全功能绕过的影响。

注意：Tenable 正在测试供应商公告中提及的 DBX 更新（于 2021 年 3 月 2 日发布）中添加的预期签名是否存在。

遠端 Windows 主機缺少安全開機 DBX 的安全性更新。因此，會受到多個弱點影響：

  - 在 grub2 2.06 之前版本中發現一個缺陷。rmmod 實作允許在不檢查是否有任何其他相依模組仍在載入的情況下，卸載作為相依項的模組，進而導致釋放後使用情形。這可允許執行任意程式碼或繞過安全開機保護。此弱點對於資料的機密性和完整性以及系統可用性威脅最大。
    (CVE-2020-25632)

  - 在 grub2 2.06 之前版本中發現一個缺陷。功能表轉譯程式碼中的 Setparam_prefix() 會根據表達引用的單引號需要 3 個字元 (實際上需要 4 個字元) 的假設來執行長度計算，這允許攻擊者透過輸入中每個引號佔用 1 個位元組來損毀記憶體。此弱點對於資料的機密性和完整性以及系統可用性威脅最大。(CVE-2021-20233)


此外，主機還受到安全開機中其他數個安全性功能繞過的影響。

注意：Tenable 正在測試 2021 年 3 月 2 日廠商公告中提及的 DBX 更新中新增的預期簽章是否存在。

リモートのWindowsホストにセキュアブートDBXの更新プログラムがありません。そのため、以下の複数の脆弱性の影響を受けます。

  - 2.06より前のバージョンでgrub2に欠陥が見つかりました。rmmodの実装により、他の依存モジュールがまだロードされているかどうかをチェックせずに、依存関係として使用されているモジュールをアンロードできるため、Use-After-Freeシナリオが発生します。これにより、任意のコードが実行されたり、セキュアブート保護がバイパスされたりする可能性があります。この脆弱性が最大の脅威となるのは、データの機密性と整合性、ならびにシステムの可用性です。
    (CVE-2020-25632)

  - 2.06より前のバージョンでgrub2に欠陥が見つかりました。メニューレンダリングコードのSetparam_prefix()は、引用符で囲まれた一重引用符を表現するには3文字を必要とし、実際には4文字を必要とするという仮定で、長さの計算を実行します。これにより、攻撃者が入力の各引用につき1バイトメモリを破損できます。この脆弱性が最大の脅威となるのは、データの機密性と整合性、ならびにシステムの可用性です。(CVE-2021-20233)


さらに、ホストはセキュアブートの他のいくつかのセキュリティ機能バイパスによる影響を受けます。

注意: Tenable は、ベンダーアドバイザリに記載された 2021 年 3 月 2 日公開の DBX の更新プログラムに追加済みの予期される署名の有無をテストしています。

An update of the grub2 package has been released.

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.

ID	Name	Product	Family	Published	Updated	Severity
423933	Alpine: multiple grub packages: security update to 2.06-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	4/4/2025	7/2/2026	high
423933	Alpine: multiple grub packages: security update to 2.06-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	4/4/2025	7/2/2026	high
139239	安全启动中的 Windows 安全功能绕过 (BootHole)	Nessus	Windows	7/31/2020	7/17/2026	high
139239	安全開機中的 Windows 安全性功能繞過 (BootHole)	Nessus	Windows	7/31/2020	7/17/2026	high
139239	セキュアブートにおけるWindowsセキュリティ機能のバイパス（BootHole）	Nessus	Windows	7/31/2020	7/17/2026	high
148024	Photon OS 4.0: Grub2 PHSA-2021-4.0-0001	Nessus	PhotonOS Local Security Checks	3/24/2021	8/22/2025	high
146996	Photon OS 3.0: Grub2 PHSA-2021-3.0-0202	Nessus	PhotonOS Local Security Checks	3/3/2021	8/22/2025	high
139239	Windows Security Feature Bypass in Secure Boot (BootHole)	Nessus	Windows	7/31/2020	7/17/2026	high
148339	Photon OS 2.0: Grub2 PHSA-2021-2.0-0334	Nessus	PhotonOS Local Security Checks	4/7/2021	7/22/2024	high

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