What’s Vulnerable › Vulnerabilities
CVE-2020-27749
- Severity: medium (CVSS 6.7 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.6% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2021-03-03 · updated 2026-06-17
- Weakness: CWE-121
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.
Affected products
- Fedoraproject Fedora: 33, 34
- grub2: before 2.06 — fixed in 2.06
- NetApp ONTAP Select Deploy administration utility: all versions
- Red Hat Enterprise Linux: 7.0, 8.0
- RedHat Enterprise Linux Server Aus: 7.2, 7.3, 7.4, 7.6, 7.7, 8.2
- RedHat Enterprise Linux Server Eus: 7.6, 7.7, 8.1
- RedHat Enterprise Linux Server Tus: 7.4, 7.6, 7.7, 8.2
- RedHat Enterprise Linux Workstation: 7.0
How to fix
Upgrade to a fixed version: grub2 2.06. Check the vendor advisory for mitigations.
References
- https://bugzilla.redhat.com/show_bug.cgi?id=1899966
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZWZ36QK4IKU6MWDWNOOWKPH3WXZBHT2R/
- https://security.gentoo.org/glsa/202104-05
- https://security.netapp.com/advisory/ntap-20220325-0001/
- https://bugzilla.redhat.com/show_bug.cgi?id=1899966
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZWZ36QK4IKU6MWDWNOOWKPH3WXZBHT2R/
- https://security.gentoo.org/glsa/202104-05
- https://security.netapp.com/advisory/ntap-20220325-0001/
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