Buffer overflow in GNU Grub2
CVE-2020-27749
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.7 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.006 (45.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 45.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000
Affected products
- GNU Grub2
- NetApp Ontap Select Deploy Administration Utility
- Fedoraproject Fedora — versions 33, 34
- Red Hat Enterprise Linux — versions 7.0, 8.0
- Red Hat Enterprise Linux Server Aus — versions 7.2, 7.3, 7.4
- Red Hat Enterprise Linux Server Eus — versions 7.6, 7.7, 8.1
- Red Hat Enterprise Linux Server Tus — versions 7.4, 7.6, 7.7
- Red Hat Enterprise Linux Workstation — versions 7.0
- Grub2 — versions grub 2.06
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugzilla.redhat.com/show_bug.cgi (Patch, Third Party Advisory, Issue Tracking)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- security.gentoo.org/glsa/202104-05 (vendor-advisory, Third Party Advisory)
- security.netapp.com/advisory/ntap-20220325-0001/ (Third Party Advisory)
Frequently asked questions
- What is CVE-2020-27749?
- CVE-2020-27749 is a medium-severity vulnerability in GNU Grub2, classified under Stack-based Buffer Overflow. CVSS score: 6.7/10. Published 2021-03-03.
- How severe is CVE-2020-27749?
- Medium severity. CVSS v3 base score is 6.7 out of 10.
- Is CVE-2020-27749 known to be exploited?
- 25 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.