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CVE-2021-33645

25
FAUCET Score

CVE-2021-33645 is a memory leak vulnerability in the th_read() function of libtar, affecting various Fedora and OpenEuler distributions. This high-severity flaw (CVSS 7.5) allows an unauthenticated attacker to cause a denial of service by exhausting system memory. There is currently no evidence of active exploitation, publicly available exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.2.21CPE matchmatch criteria
cpe:2.3:a:feep:libtar:*:*:*:*:*:*:*:*
20.03CPE matchmatch criteria
cpe:2.3:o:openatom:openeuler:20.03:sp1:*:*:lts:*:*:*
20.03CPE matchmatch criteria
cpe:2.3:o:openatom:openeuler:20.03:sp3:*:*:lts:*:*:*
22.03CPE matchmatch criteria
cpe:2.3:o:openatom:openeuler:22.03:*:*:*:lts:*:*:*
35CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.44%
Probability of exploitation in next 30 days
EPSS Percentile
70.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0144 is in the 52nd percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (13)

microsoftpatch availablevia msrc
Product: Azure Linux 3.0 ARMFixed in: 1.2.20-11
microsoftpatch availablevia msrc
Product: 18871-16823Fixed in: 1.2.20-10
microsoftpatch availablevia msrc
Product: 18850-17084Fixed in: 1.2.20-11
microsoftpatch availablevia msrc
Product: 18870-16820Fixed in: 1.2.20-10
microsoftpatch availablevia msrc
Product: cm1 libtar 1.2.20-10 on CBL Mariner 1.0Fixed in: 1.2.20-10
microsoftpatch availablevia msrc
Product: cbl2 libtar 1.2.20-10 on CBL Mariner 2.0Fixed in: 1.2.20-10
microsoftpatch availablevia msrc
Product: azl3 libtar 1.2.20-11 on Azure Linux 3.0Fixed in: 1.2.20-11
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 1.2.20-10
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 1.2.20-10
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 x64Fixed in: 1.2.20-10
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 ARMFixed in: 1.2.20-10
microsoftpatch availablevia msrc
Product: Azure Linux 3.0 x64Fixed in: 1.2.20-11
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: libtar-0:1.2.20-17.el8
View patch

Vendor Advisories (3)

microsoft2024-Jun/CVE-2021-33645

CVE-2021-33645

Jun 11, 2024
redhatCVE-2021-33645Moderate

libtar: memory leak found in th_read() function

Aug 10, 2022
microsoft2022-Aug/CVE-2021-33645Important

The th_read() function doesn’t free a variable t->th_buf.gnu_longlink after allocating memory which may cause a memory leak.

Aug 9, 2022

References

lists.debian.org / debian-lts-announce/2025/01/msg00026.html
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/4S4PJRCJLEAWN2EKXGLSOBTL7O57V7NC
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/5YSHZY753R7XW6CIKJVAWI373WW3YRRJ
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/7Q26QDNOJDOFYWMJWEIK5XR62M2FF6IJ
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/7WX5YE66CT7Y5C2HTHXSFDKQWYWYWJ2T
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/OD4HEBSTI22FNYKOKK7W3X6ZQE6FV3XC
openeuler.org / en/security/safety-bulletin/detail.html
Third Party Advisory