Is CVE-2021-33643 in the CISA KEV catalog?

No. CVE-2021-33643 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-33643?

CVE-2021-33643 has a CVSS v3 base score of 9.1 (CRITICAL).

What is the EPSS score for CVE-2021-33643?

CVE-2021-33643 has an EPSS score of 1.33% (68th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-33643?

Upgrade libtar on debian 11 to 1.2.20-8+deb12u1~deb11u1 or later. Fixes are available for 11 affected products.

CVE & CISA-KEV Catalog

CVE-2021-33643

CRITICAL

9.1

CVSS v3

NVD

Description

An attacker who submits a crafted tar file with size in header struct being 0 may be able to trigger an calling of malloc(0) for a variable gnu_longlink, causing an out-of-bounds read.

CWE-125Out-of-bounds Read

How to fix

Remediation Available

libtarDebian

Fixed in:1.2.20-8+deb12u1~deb11u1CVE-2021-33643

Fixed in:1.2.20-8+deb12u1CVE-2021-33643

libtarRed Hat / RHEL

Fixed in:0:1.2.20-17.el8RHSA-2023:2898

libtarRocky

Fixed in:0:1.2.20-17.el8RHSA-2023:2898

libtar-debuginfoRed Hat / RHEL

Fixed in:0:1.2.20-17.el8RHSA-2023:2898

libtar-debuginfoRocky

Fixed in:0:1.2.20-17.el8RHSA-2023:2898

libtar-debugsourceRocky

Fixed in:0:1.2.20-17.el8RHSA-2023:2898

libtar-debugsourceRed Hat / RHEL

Fixed in:0:1.2.20-17.el8RHSA-2023:2898

libtarUbuntu

Fixed in:1.2.20-4ubuntu0.1~esm1USN-7398-1

Fixed in:1.2.20-7ubuntu0.1~esm1USN-7398-1

Fixed in:1.2.20-8ubuntu0.20.04.1USN-7398-1

Fixed in:1.2.20-8ubuntu0.22.04.1USN-7398-1

Fixed in:1.2.20-8.1ubuntu0.24.04.1USN-7398-1

libtar-devUbuntu

Fixed in:1.2.20-4ubuntu0.1~esm1USN-7398-1

Fixed in:1.2.20-7ubuntu0.1~esm1USN-7398-1

Fixed in:1.2.20-8ubuntu0.20.04.1USN-7398-1

Fixed in:1.2.20-8ubuntu0.22.04.1USN-7398-1

Fixed in:1.2.20-8.1ubuntu0.24.04.1USN-7398-1

libtar0Ubuntu

Fixed in:1.2.20-4ubuntu0.1~esm1USN-7398-1

Fixed in:1.2.20-7ubuntu0.1~esm1USN-7398-1

Fixed in:1.2.20-8ubuntu0.20.04.1USN-7398-1

Fixed in:1.2.20-8ubuntu0.22.04.1USN-7398-1

libtar0t64Ubuntu

Fixed in:1.2.20-8.1ubuntu0.24.04.1USN-7398-1

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 VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

1.33%probability of exploitation in 30 days

68thpercentile

Moderate risk: more likely to be exploited than 68% of all known CVEs.

References

Third-Party Advisory1

openeuler.org

Other references6

Related Vulnerabilities

Other CWE-125 (Out-of-bounds Read) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2014-0160	High	7.5	100%	KEV	Fix
CVE-2025-5777	High	7.5	100%	KEV + Ransom	Fix
CVE-2021-4034	High	7.8	95%	KEV	Fix
CVE-2023-21769	High	7.5	92%	-	Fix
CVE-2023-49285	High	8.6	89%	-	Fix
CVE-2020-8794	Critical	9.8	89%	-	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 2026-06-23.