Is CVE-2021-3696 in the CISA KEV catalog?

No. CVE-2021-3696 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-3696?

CVE-2021-3696 has a CVSS v3 base score of 4.5 (MEDIUM).

What is the EPSS score for CVE-2021-3696?

CVE-2021-3696 has an EPSS score of 0.47% (37th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-3696?

Upgrade grub2 on debian 11 to 2.06-3~deb11u1 or later. Fixes are available for 11 affected products.

CVE & CISA-KEV Catalog

CVE-2021-3696

MEDIUM

4.5

CVSS v3

NVD

Description

A heap out-of-bounds write may heppen during the handling of Huffman tables in the PNG reader. This may lead to data corruption in the heap space. Confidentiality, Integrity and Availablity impact may be considered Low as it's very complex to an attacker control the encoding and positioning of corrupted Huffman entries to achieve results such as arbitrary code execution and/or secure boot circumvention. This flaw affects grub2 versions prior grub-2.12.

CWE-787Out-of-bounds Write

How to fix

Remediation Available

grub2Debian

Fixed in:2.06-3~deb11u1CVE-2021-3696

Fixed in:2.06-3CVE-2021-3696

grub-efi-amd64Ubuntu

Fixed in:2.06-2ubuntu14.1USN-6355-1

grub-efi-amd64-binUbuntu

Fixed in:2.06-2ubuntu14.1USN-6355-1

grub-efi-amd64-signedUbuntu

Fixed in:1.187.3~20.04.1+2.06-2ubuntu14.1USN-6355-1

Fixed in:1.187.3~22.04.1+2.06-2ubuntu14.1USN-6355-1

grub-efi-arm64Ubuntu

Fixed in:2.06-2ubuntu14.1USN-6355-1

grub-efi-arm64-binUbuntu

Fixed in:2.06-2ubuntu14.1USN-6355-1

grub-efi-arm64-signedUbuntu

Fixed in:1.187.3~20.04.1+2.06-2ubuntu14.1USN-6355-1

Fixed in:1.187.3~22.04.1+2.06-2ubuntu14.1USN-6355-1

grub2-signedUbuntu

Fixed in:1.187.3~20.04.1USN-6355-1

Fixed in:1.187.3~22.04.1USN-6355-1

grub2-unsignedUbuntu

Fixed in:2.06-2ubuntu14.1USN-6355-1

shimUbuntu

Fixed in:15.7-0ubuntu1USN-6355-1

shim-signedUbuntu

Fixed in:1.40.9USN-6355-1

Fixed in:1.51.3USN-6355-1

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 ComplexityHigh

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityLow

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

Exploit Intelligence

0.47%probability of exploitation in 30 days

37thpercentile

Low risk: more likely to be exploited than 37% of all known CVEs.

References

Third-Party Advisory3

Related Vulnerabilities

Other CWE-787 (Out-of-bounds Write) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-22457	Critical	9.0	100%	KEV + Ransom	Fix
CVE-2025-0282	Critical	9.0	100%	KEV + Ransom	-
CVE-2015-3113	Critical	9.8	100%	KEV	Fix
CVE-2021-20038	Critical	9.8	100%	KEV + Ransom	-
CVE-2023-4863	High	8.8	100%	KEV	Fix
CVE-2020-16040	Medium	6.5	100%	-	Fix

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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.