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CVE-2021-33640· NVD / CVE Program· CNA openEuler

After tar_close(), libtar.c releases the memory pointed to by pointer t.

After tar_close(), libtar.c releases the memory pointed to by pointer t. After tar_close() is called in the list() function, it continues to use pointer t: free_longlink_longname(t->th_buf) . As a result, the released memory is used (use-after-free).

CriticalCVSS 9.8 · v3.1—No exploit Fix available

Noroxi analysis

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Published
Dec 19, 2022
Updated
Jun 16, 2026
EPSS
0.7% · 50th percentile
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Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.7%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
9.8
CNA · openEuler
6.2
3.6 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
openatomopeneuler
fedoraprojectfedora

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • fedoraproject fedora36
  • fedoraproject fedora37
  • openatom openeuler20.03
  • openatom openeuler22.03

Versions reported by the vendor

Affected version ranges reported by the assigning authority (openEuler). Independent of NVD's CPE analysis and usually ahead of it.

  • openEuler openEuler 20.03 LTS SP1

    • libtar 1.2.20-19affected

  • openEuler openEuler 20.03 LTS SP3

    • libtar 1.2.20-19affected

  • openEuler openEuler 22.03 LTS

    • libtar 1.2.20-21affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
openSUSE:Tumbleweedlibtarbefore 1.2.20-3.11.2.20-3.1

Same product

openatom: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-33631Kernel crash in EXT4 filesystem
    31Monitor
  • CVE-2021-33656When setting font with malicous data by ioctl cmd PIO_FONT,kernel will write memory out of bounds.
    27Monitor
  • CVE-2021-33630NULL-ptr-deref in network sched
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
opensuse:libtar1.2.20-3.1 · openSUSE:TumbleweedPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records