CVE-2021-3695: High severity GNU GRUB2 vulnerability
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.
Other sources
A flaw was found in grub 2, where a crafted 16-bit grayscale PNG image may lead to an out-of-bounds write. This flaw allows an attacker to corrupt the data on the heap portion of the grub2's memory, leading to possible code execution and the circumvention of the secure boot mechanism.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/grub2to a version that resolves this vulnerability.Fixed in 2.06-3~deb10u1Fixed in 2.06-3~deb10u3Fixed in 2.06-3~deb11u5Fixed in 2.06-3~deb11u4Fixed in 2.06-13Fixed in 2.12~rc1-9 - Upgrade
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redhat/grub2to a version that resolves this vulnerability.Fixed in 1:2.02-123.el8_6.8 - Upgrade
Upgrade
redhat/grub2to a version that resolves this vulnerability.Fixed in 1:2.02-87.el8_1.10 - Upgrade
Upgrade
redhat/grub2to a version that resolves this vulnerability.Fixed in 1:2.02-87.el8_2.10 - Upgrade
Upgrade
redhat/grub2to a version that resolves this vulnerability.Fixed in 1:2.02-99.el8_4.9 - Upgrade
Upgrade
redhat/grub2to a version that resolves this vulnerability.Fixed in 1:2.06-27.el9_0.7 - Upgrade
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redhat/grubto a version that resolves this vulnerability.Fixed in 2.12 - Upgrade
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grub2to a version that resolves this vulnerability.Fixed in 2.12
Event History
Parent advisories
This vulnerability appears in the following advisories.
Frequently Asked Questions
What is CVE-2021-3695?
CVE-2021-3695 is a vulnerability in grub 2 that may lead to heap data corruption or arbitrary code execution.
How severe is CVE-2021-3695?
CVE-2021-3695 has a severity rating of 7 (high).
What is the affected software?
The affected software includes Redhat Enterprise Linux versions 8.0 to 8.6, Redhat Codeready Linux Builder, and Netapp Ontap Select Deploy Administration Utility.
How can CVE-2021-3695 be exploited?
CVE-2021-3695 can be exploited through a crafted 16-bit grayscale PNG image that triggers an out-of-bounds write in the heap area.
Where can I find more information about CVE-2021-3695?
You can find more information about CVE-2021-3695 on the CVE website, NIST National Vulnerability Database, Redhat Bugzilla, and Redhat Access Portal.