GRUB2: avoid loading unsigned kernels when GRUB is booted directly under secureboot without shim

Description

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.

Scores

EPSS (exploitation in 30 days)

1.4% · top 28% of all CVEs (6 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.4.

Weakness

• CWE-347 Improper Verification of Cryptographic Signature (opens in a new tab)All about CWE-347 and its CVEs

Affected products

• Ubuntu · grub2 in Ubuntu

  • affected 20.04 LTS – < 2.04-1ubuntu26.1
  • affected 18.04 LTS – < 2.02-2ubuntu8.16
  • affected 16.04 LTS – < 2.02~beta2-36ubuntu3.26
  • affected 14.04 ESM – < 2.02~beta2-9ubuntu1.20

References (20)

• https://www.eclypsium.com/2020/07/29/theres-a-hole-in-the-boot/ (opens in a new tab)x_refsource_CONFIRMx_transferred
• https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/GRUB2SecureBootBypass (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
• http://ubuntu.com/security/notices/USN-4432-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
• https://www.debian.org/security/2020-GRUB-UEFI-SecureBoot (opens in a new tab)vendor-advisoryx_refsource_DEBIANx_transferred
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV200011 (opens in a new tab)x_refsource_CONFIRMx_transferred
• https://access.redhat.com/security/vulnerabilities/grub2bootloader (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
• https://www.suse.com/c/suse-addresses-grub2-secure-boot-issue/ (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
• https://www.suse.com/support/kb/doc/?id=000019673 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
• https://www.openwall.com/lists/oss-security/2020/07/29/3 (opens in a new tab)x_refsource_CONFIRMx_transferred
• https://lists.gnu.org/archive/html/grub-devel/2020-07/msg00034.html (opens in a new tab)x_refsource_CONFIRMx_transferred
• [oss-security] 20200729 multiple secure boot grub2 and linux kernel vulnerabilities (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
• https://security.netapp.com/advisory/ntap-20200731-0008/ (opens in a new tab)x_refsource_CONFIRMx_transferred
• USN-4432-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
• openSUSE-SU-2020:1280 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
• openSUSE-SU-2020:1282 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
• [oss-security] 20210302 Multiple GRUB2 vulnerabilities (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
• GLSA-202104-05 (opens in a new tab)vendor-advisoryx_refsource_GENTOOx_transferred
• [oss-security] 20210916 Containers-optimized OS (COS) membership in the linux-distros list (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
• [oss-security] 20210917 Re: Containers-optimized OS (COS) membership in the linux-distros list (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
• [oss-security] 20210920 Re: Containers-optimized OS (COS) membership in the linux-distros list (opens in a new tab)mailing-listx_refsource_MLISTx_transferred

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2020-15705](https://trackcve.app/badge/CVE-2020-15705.svg)](https://trackcve.app/cve/CVE-2020-15705)

Record last updated 17 Sept 2024, 00:06 UTC.