CVE-2021-33640

Local process crash via freed libtar pointer

Published Dec 19, 2022 · Updated Apr 17, 2025

Use-after-free in libtar on openEuler 20.03 LTS SP1, 20.03 LTS SP3, and 22.03 LTS allows local users to crash archive-listing processes. In libtar.c, list() calls tar_close(), which frees the TAR object, then passes t->th_buf from that freed object to free_longlink_longname(). Exploitation requires local execution of the affected archive-listing path and interrupts only that process; no data disclosure or modification is reported.

CVSS severity6.2
Medium
EPSS probability0.65%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in libtar on openEuler 20.03 LTS SP1, 20.03 LTS SP3, and 22.03 LTS allows local users to crash archive-listing processes. In libtar.c, list() calls tar_close(), which frees the TAR object, then passes t->th_buf from that freed object to free_longlink_longname(). Exploitation requires local execution of the affected archive-listing path and interrupts only that process; no data disclosure or modification is reported.

The record

CVE
CVE-2021-33640
Published
Dec 19, 2022
Updated
Apr 17, 2025
Vendor
openEuler
Product
openEuler
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 19, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 17, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=libtar 1.2.20-19
  2. Affected versionversion=libtar 1.2.20-21

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

openEuler · openEulerversion=libtar 1.2.20-19; version=libtar 1.2.20-21

Published CVSS scores

6.2openEulerCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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