Security readout for executives and security teams
Plain-English summary
CVE-2021-33640 is a memory-safety flaw in libtar that can crash affected software after tar_close() frees an object that later code still uses. The documented impact is availability loss, not data theft or privilege escalation. Treat it as a stability and service-continuity issue where affected libtar packages are present.
Executive priority
Handle through normal patch management, with higher priority for shared systems or workflows that process untrusted archives. The main business risk is local denial of service rather than compromise of confidentiality or integrity, based on the provided sources.
Technical view
In libtar, list() calls tar_close(), then continues using pointer t through free_longlink_longname(t->th_buf), creating a use-after-free. CVSS 3.1 is 6.2 with local attack vector, low complexity, no privileges or user interaction, unchanged scope, and high availability impact.
Likely exposure
Exposure is most likely on systems running the listed openEuler libtar packages: 22.03 LTS libtar 1.2.20-21, 20.03 LTS SP1 libtar 1.2.20-19, or 20.03 LTS SP3 libtar 1.2.20-19. Fedora advisories also indicate relevant packaged updates existed.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The CVSS vector is local, so practical risk depends on whether local users or local processing paths can trigger affected libtar behavior. Public sources here support availability impact only.
Researcher notes
Evidence is limited to a concise use-after-free description, CVSS metadata, affected openEuler package versions, and Fedora advisory links. The bundle does not provide exploit details, fixed version mapping, or proof of active exploitation, so validation should stay package- and vendor-advisory focused.
Mitigation direction
- Inventory systems for libtar on the listed openEuler and Fedora platforms.
- Apply vendor-provided libtar updates from openEuler or Fedora where applicable.
- Check vendor advisories for fixed package versions before approving exceptions.
- Prioritize systems where libtar processes untrusted or user-supplied tar archives.
Validation and detection
- Confirm installed libtar package versions against the affected versions listed by openEuler.
- Verify package update status using approved asset or patch management records.
- Review applications or scripts that invoke libtar on local tar archives.
- Document any exceptions with vendor advisory status and compensating controls.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-416: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-33640 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.2 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H2.53.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.2MediumVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.openeuler.org/en/security/cve/detail/?cveId=CVE-2021-33640&packageName=libtarCVE reference
- FEDORA-2022-88772d0a2dCVE reference · vendor-advisory
- FEDORA-2022-ccc68b06ccCVE reference · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.