CVE-2021-37701

Arbitrary file overwrite via poisoned directory cache

Published Aug 31, 2021 · Updated Aug 4, 2024

Path traversal in npm node-tar before 4.4.16, 5.0.0 through 5.0.7, and 6.0.0 through 6.1.6 allows attackers to overwrite arbitrary files. The extraction cache treats backslashes as separators on POSIX systems and prunes names case-sensitively, leaving a stale directory entry after a matching directory is replaced by a symlink. Exploitation requires processing a crafted archive; later entries then follow the symlink outside the extraction directory, enabling file creation or overwrite and resulting code execution where overwritten files are executed.

CVSS severity8.2
High
EPSS probability3.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in npm node-tar before 4.4.16, 5.0.0 through 5.0.7, and 6.0.0 through 6.1.6 allows attackers to overwrite arbitrary files. The extraction cache treats backslashes as separators on POSIX systems and prunes names case-sensitively, leaving a stale directory entry after a matching directory is replaced by a symlink. Exploitation requires processing a crafted archive; later entries then follow the symlink outside the extraction directory, enabling file creation or overwrite and resulting code execution where overwritten files are executed.

The record

CVE
CVE-2021-37701
Published
Aug 31, 2021
Updated
Aug 4, 2024
Vendor
npm
Product
node-tar
Classifications
CWE-59, CWE-22, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 31, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=< 4.4.16
  2. Affected versionversion=>= 5.0.0, < 5.0.8
  3. Affected versionversion=>= 6.0.0, < 6.1.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

npm · node-tarversion=< 4.4.16; version=>= 5.0.0, < 5.0.8; version=>= 6.0.0, < 6.1.7

Published CVSS scores

8.2GitHubCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-59Improper Link Resolution Before File Access ('Link Following')
CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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