Use After Free in GNU Grub2
CVE-2020-15706
GRUB2 contains a race condition in grub_script_function_create() leading to a use-after-free vulnerability which can be triggered by redefining a function whilst the same function is already executing, leading to arbitrary code execution and secure boot restriction bypass. This issue affects GRUB2 version 2.04 and prior versions.
Vulnerability class: Race Condition
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.4 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.010 (60.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 60.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000
Affected products
- GNU Grub2
- Microsoft Windows 10 — versions 1607, 1709, 1803
- Microsoft Windows 8.1
- Microsoft Windows Rt 8.1
- Microsoft Windows Server 2012 — versions r2
- Microsoft Windows Server 2016 — versions 1903, 1909, 2004
- Microsoft Windows Server 2019
- Canonical Ubuntu Linux — versions 14.04, 16.04, 18.04
- Debian Linux — versions 10.0
- openSUSE Leap — versions 15.1, 15.2
Weakness classification (CWE)
Public proof-of-concept exploits
References
- www.eclypsium.com/2020/07/29/theres-a-hole-in-the-boot/ (Third Party Advisory)
- wiki.ubuntu.com/SecurityTeam/KnowledgeBase/GRUB2SecureBootBypass (vendor-advisory, Third Party Advisory)
- ubuntu.com/security/notices/USN-4432-1 (vendor-advisory, Third Party Advisory)
- www.debian.org/security/2020-GRUB-UEFI-SecureBoot (vendor-advisory, Third Party Advisory)
- portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV200011 (Patch, Third Party Advisory, Vendor Advisory)
- access.redhat.com/security/vulnerabilities/grub2bootloader (vendor-advisory, Third Party Advisory)
- www.suse.com/c/suse-addresses-grub2-secure-boot-issue/ (vendor-advisory, Third Party Advisory)
- www.suse.com/support/kb/doc/ (vendor-advisory, Third Party Advisory)
- www.openwall.com/lists/oss-security/2020/07/29/3 (Mailing List, Third Party Advisory)
- lists.gnu.org/archive/html/grub-devel/2020-07/msg00034.html (Issue Tracking, Vendor Advisory)
Frequently asked questions
- What is CVE-2020-15706?
- CVE-2020-15706 is a medium-severity vulnerability in GNU Grub2, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 6.4/10. Published 2020-07-29.
- How severe is CVE-2020-15706?
- Medium severity. CVSS v3 base score is 6.4 out of 10.
- Is CVE-2020-15706 known to be exploited?
- 13 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.