Buffer overflow in GNU Grub2
CVE-2021-3695
A crafted 16-bit grayscale PNG image may lead to a out-of-bounds write in the heap area. An attacker may take advantage of that to cause heap data corruption or eventually arbitrary code execution and circumvent secure boot protections. This issue has a high complexity to be exploited as an attacker needs to perform some triage over the heap layout to achieve signifcant results, also the values written into the memory are repeated three times in a row making difficult to produce valid payloads. This flaw affects grub2 versions prior grub-2.12.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.5 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.005 (38.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 38.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- GNU Grub2
- NetApp Ontap Select Deploy Administration Utility
- Fedoraproject Fedora — versions 36
- Red Hat Codeready Linux Builder
- Red Hat Developer Tools — versions 1.0
- Red Hat Enterprise Linux — versions 8.0, 8.1, 8.4
- Red Hat Enterprise Linux Eus — versions 8.2, 8.4, 8.6
- Red Hat Enterprise Linux For Power Little Endian — versions 8.0, 9.0
- Red Hat Enterprise Linux For Power Little Endian Eus — versions 8.2, 8.4, 8.6
- Red Hat Enterprise Linux Server Aus — versions 8.2, 8.4, 8.6
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugzilla.redhat.com/show_bug.cgi (Third Party Advisory, Issue Tracking)
- security.gentoo.org/glsa/202209-12 (vendor-advisory, Third Party Advisory)
- security.netapp.com/advisory/ntap-20220930-0001/ (Third Party Advisory)
Frequently asked questions
- What is CVE-2021-3695?
- CVE-2021-3695 is a medium-severity vulnerability in GNU Grub2, classified under Out-of-bounds Write. CVSS score: 4.5/10. Published 2022-07-06.
- How severe is CVE-2021-3695?
- Medium severity. CVSS v3 base score is 4.5 out of 10.
- Is CVE-2021-3695 known to be exploited?
- 19 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.