CVE-2020-10713 – CVE-2020-10713 is a buffer overflow vulnerabili... (How to Fix)

Q: What is the severity of CVE-2020-10713?

CVE-2020-10713 has a CVSS score of 8.2 (HIGH). CVE-2020-10713 is a buffer overflow vulnerability in GRUB2 bootloader versions before 2.06 that allows attackers with physical or administrative access to bypass Secure Boot protections and execute arbitrary code during boot. This enables loading of malicious kernels or boot components, compromising system integrity from the earliest boot stage. Affected systems include any using vulnerable GRUB2 versions with Secure Boot enabled.

📋 TL;DR

CVE-2020-10713 is a buffer overflow vulnerability in GRUB2 bootloader versions before 2.06 that allows attackers with physical or administrative access to bypass Secure Boot protections and execute arbitrary code during boot. This enables loading of malicious kernels or boot components, compromising system integrity from the earliest boot stage. Affected systems include any using vulnerable GRUB2 versions with Secure Boot enabled.

💻 Affected Systems

Products:

GRUB2
Linux distributions using GRUB2
UEFI systems with Secure Boot

Versions: All GRUB2 versions prior to 2.06

Operating Systems: Linux distributions (RHEL, CentOS, Ubuntu, Debian, SUSE), Any OS using GRUB2 as bootloader

Default Config Vulnerable: ⚠️ Yes

Notes: Only exploitable when Secure Boot is enabled and attacker has physical access or administrative privileges to modify boot configuration.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system compromise via persistent bootkit that survives OS reinstallation, enabling data theft, ransomware deployment, and undetectable backdoors.

🟠

Likely Case

Attacker with physical access or administrative privileges installs bootkit to maintain persistence, bypass security controls, and gain elevated privileges.

🟢

If Mitigated

With proper patching and Secure Boot enforcement, impact is limited to denial of service if attacker attempts exploitation but cannot bypass verification.

🌐 Internet-Facing: LOW - Requires physical access or administrative privileges on target system; not directly exploitable over network.

🏢 Internal Only: MEDIUM - Insider threats or compromised administrative accounts could exploit this for persistent access and privilege escalation.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires physical access or administrative privileges to modify boot configuration (PXE, local boot device). Proof-of-concept code has been published demonstrating Secure Boot bypass.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: GRUB2 version 2.06 or later

Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1825243

Restart Required: Yes

Instructions:

1. Update GRUB2 package to version 2.06 or later using distribution package manager. 2. Update UEFI/BIOS firmware if vendor provides Secure Boot DBX updates. 3. Regenerate initramfs and reinstall GRUB. 4. Reboot system to apply changes.

🔧 Temporary Workarounds

Disable GRUB command line editing

linux

Prevents injection of malicious commands during boot by restricting GRUB command line access

Edit /etc/default/grub and add: GRUB_DISABLE_OS_PROBER=true
GRUB_TERMINAL=console
Run: grub2-mkconfig -o /boot/grub2/grub.cfg

Enable UEFI Secure Boot with DBX revocation

all

Update UEFI revocation list to block vulnerable GRUB2 binaries from loading

Check for firmware updates from hardware vendor
Install UEFI DBX updates if available

🧯 If You Can't Patch

Restrict physical access to systems and secure boot media
Implement strict administrative access controls and monitor for unauthorized boot configuration changes

🔍 How to Verify

Check if Vulnerable:

Check GRUB2 version with: grub2-install --version or rpm -q grub2

Check Version:

grub2-install --version | head -1

Verify Fix Applied:

Verify GRUB2 version is 2.06 or later and check that Secure Boot is still functional

📡 Detection & Monitoring

Log Indicators:

Unexpected GRUB configuration changes
Secure Boot validation failures in kernel logs
Boot process anomalies in systemd-journal

Network Indicators:

Unauthorized PXE boot server activity
Unexpected network boot attempts

SIEM Query:

source="kernel" AND "Secure Boot" AND ("failed" OR "invalid") OR source="grub" AND "configuration modified"

📊 Metadata

CVE ID: CVE-2020-10713

CVSS v3 Score: 8.2 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

CWE: CWE-120

Published: July 30, 2020

Last Updated: November 21, 2024

🔗 References

http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00016.html Mailing List,Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00017.html Mailing List,Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/07/29/3 Mailing List,Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1825243 Issue Tracking,Third Party Advisory
https://cve.openeuler.org/#/CVEInfo/CVE-2020-10713 Broken Link
https://eclypsium.com/2020/07/29/theres-a-hole-in-the-boot/ Technical Description,Third Party Advisory
https://kb.vmware.com/s/article/80181 Third Party Advisory
https://security.gentoo.org/glsa/202104-05 Third Party Advisory
https://security.netapp.com/advisory/ntap-20200731-0008/ Third Party Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-grub2-code-exec-xLePCAPY Third Party Advisory
https://usn.ubuntu.com/4432-1/ Third Party Advisory
https://www.debian.org/security/2020/dsa-4735 Third Party Advisory
https://www.kb.cert.org/vuls/id/174059 Third Party Advisory,US Government Resource
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00016.html Mailing List,Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00017.html Mailing List,Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/07/29/3 Mailing List,Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1825243 Issue Tracking,Third Party Advisory
https://cve.openeuler.org/#/CVEInfo/CVE-2020-10713 Broken Link
https://eclypsium.com/2020/07/29/theres-a-hole-in-the-boot/ Technical Description,Third Party Advisory
https://kb.vmware.com/s/article/80181 Third Party Advisory
https://security.gentoo.org/glsa/202104-05 Third Party Advisory
https://security.netapp.com/advisory/ntap-20200731-0008/ Third Party Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-grub2-code-exec-xLePCAPY Third Party Advisory
https://usn.ubuntu.com/4432-1/ Third Party Advisory
https://www.debian.org/security/2020/dsa-4735 Third Party Advisory
https://www.kb.cert.org/vuls/id/174059 Third Party Advisory,US Government Resource

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