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CVE Record

CVE-2018-20834: A vulnerability was found in node-tar before version 4.4.2 (excluding version 2.2.2).

A vulnerability was found in node-tar before version 4.4.2 (excluding version 2.2.2). An Arbitrary File Overwrite issue exists when extracting a tarball containing a hardlink to a file that already exists on the system, in conjunction with a later plain file with the same name as the hardlink. This plain file content replaces the existing file content. A patch has been applied to node-tar v2.2.2).

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2018-20834 affects node-tar archive extraction. A specially crafted tarball can cause an existing file on the system to be overwritten during extraction. Business impact depends on where extraction happens, what account performs it, and whether the affected workflow handles untrusted archives.

Executive priority

Prioritize if the organization processes untrusted tar archives or uses Node.js build and deployment automation extensively. Without known active exploitation or CVSS in the bundle, treat urgency as exposure-driven rather than universally critical.

Technical view

The issue is an arbitrary file overwrite in node-tar before 4.4.2, with 2.2.2 identified as patched. It involves a tarball containing a hardlink to an existing system file followed by a plain file with the same name, causing replacement of that existing file's content during extraction.

Likely exposure

Most exposure is in Node.js applications, build systems, package tooling, or services that extract tar archives using vulnerable node-tar versions, especially when archives come from users, third parties, CI inputs, or package mirrors.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation evidence. Exploitation requires a crafted tarball and a vulnerable extraction path with access to a target file. Impact can increase if extraction runs with elevated permissions.

Researcher notes

The provided record lacks CVSS, CWE, and complete affected CPE data. Analysis should focus on dependency versioning, archive trust boundaries, extraction privileges, and whether vulnerable code paths are reachable in production or build systems.

Mitigation direction

  • Upgrade node-tar to 4.4.2 or later where applicable.
  • For 2.x deployments, verify use of patched version 2.2.2.
  • Check Red Hat advisory RHSA-2019:1821 for distro-packaged remediation.
  • Avoid privileged extraction of untrusted tarballs until fixed.
  • Review vendor guidance before applying environment-specific workarounds.

Validation and detection

  • Review dependency manifests and SBOMs for vulnerable node-tar versions.
  • Identify applications or jobs that extract user-supplied tar archives.
  • Check CI, build, packaging, and deployment tooling for node-tar usage.
  • Verify runtime extraction does not run with unnecessary file permissions.
  • Confirm patched versions are deployed, not only declared.
Prepared
Confidence
medium
Sources
9

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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description · low confidence lookup

File access behavior lookup

The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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CVE-2018-20834 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

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.

0CVSS vectors
0Timeline events
0ADP providers
8Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

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