CVE & CISA-KEV Catalog

CVE-2020-27749

MEDIUM
6.7
CVSS v3
NVD

Description

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.

CWE-121Stack-based Buffer OverflowCWE-787Out-of-bounds Write

How to fix

Remediation Available
grub2Debian
Fixed in:2.04-16CVE-2020-27749
Fixed in:2.04-16CVE-2020-27749
Fixed in:2.04-16CVE-2020-27749
Fixed in:2.04-16CVE-2020-27749
grub-efi-amd64-binUbuntu
Fixed in:2.04-1ubuntu44.1.2USN-4992-1
Fixed in:2.04-1ubuntu44.2USN-4992-1
grub-efi-amd64-signedUbuntu
Fixed in:1.167~18.04.5+2.04-1ubuntu44.1.2USN-4992-1
Fixed in:1.167.2+2.04-1ubuntu44.2USN-4992-1
grub-efi-arm64-binUbuntu
Fixed in:2.04-1ubuntu44.1.2USN-4992-1
Fixed in:2.04-1ubuntu44.2USN-4992-1
grub-efi-arm64-signedUbuntu
Fixed in:1.167~18.04.5+2.04-1ubuntu44.1.2USN-4992-1
Fixed in:1.167.2+2.04-1ubuntu44.2USN-4992-1
grub2-signedUbuntu
Fixed in:1.167~18.04.5USN-4992-1
Fixed in:1.167.2USN-4992-1
grub2-unsignedUbuntu
Fixed in:2.04-1ubuntu44.1.2USN-4992-1
Fixed in:2.04-1ubuntu44.2USN-4992-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal
Attack ComplexityLow
Privileges RequiredHigh
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

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

Exploit Intelligence

0.57%probability of exploitation in 30 days
43rdpercentile

Moderate risk: more likely to be exploited than 43% of all known CVEs.

References

Other references1

Related Vulnerabilities

Other CWE-121 (Stack-based Buffer Overflow) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2025-22457Critical9.0100%KEV + RansomFix
CVE-2025-0282Critical9.0100%KEV + Ransom-
CVE-2021-20038Critical9.8100%KEV + Ransom-
CVE-2009-0927High8.897%KEVFix
CVE-2020-10924High8.887%--
CVE-2022-20705Critical10.080%--
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.