CVE Intelligence
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HIGH

CVE-2021-37701

CVE-2021-37701 — Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning using symbolic links

The npm package "tar" (aka node-tar) before versions 4.4.16, 5.0.8, and 6.1.7 has an arbitrary file creation/overwrite and arbitrary code execution vulnerability. node-tar aims to guarantee that any file whose location would be modified by a symbolic link is not extracted. This is, in part, achieved by ensuring that extracted directories are not symlinks. Additionally, in order to prevent unnecessary stat calls to determine whether a given path is a directory, paths are cached when directories are created. This logic was insufficient when extracting tar files that contained both a directory and a symlink with the same name as the directory, where the symlink and directory names in the archive entry used backslashes as a path separator on posix systems. The cache checking logic used both `\` and `/` characters as path separators, however `\` is a valid filename character on posix…

Published Updated Sources: cvelistV5, GitHub_M

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

3%

chance of exploitation in 30 days

Affects

npm

node_tar

CVSS base

8.2

HIGH

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (1)

npm

Products (1)

node tar

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
8.2CVSS 3.1HIGH——cvelistV5

Weakness & attack patterns

  • CWE-22
  • CWE-59

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

  • T1547.009Boot or Logon Autostart Execution: Shortcut Modification
  • T1574.005Hijack Execution Flow: Executable Installer File Permissions Weakness
  • T1574.010Hijack Execution Flow: Services File Permissions Weakness

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

  • Search application, proxy, and WAF logs for requests touching /overwrite.

References

6 on the record

Elsewhere on this site

  • npmevery CVE for this vendor
  • CWE-22other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.