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CVE-2021-39135— UNIX Symbolic Link (Symlink) Following in @npmcli/arborist

Quick assessment

Affected
npm arborist
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

NPM arborist是美国npm（NPM）公司的一个软件包。用于可视化存储为平面列表的分层数据。 NPM arborist 存在后置链接漏洞，该漏洞源于网络系统或产品的代码开发过程中存在设计或实现不当的问题。

CVSS 8.2 · High EPSS 0.55% · P44
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I. Basic Information for CVE-2021-39135

Vulnerability Information
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Vulnerability Title
UNIX Symbolic Link (Symlink) Following in @npmcli/arborist
Source: CVE Program / CVE List V5
Vulnerability Description
`@npmcli/arborist`, the library that calculates dependency trees and manages the node_modules folder hierarchy for the npm command line interface, aims to guarantee that package dependency contracts will be met, and the extraction of package contents will always be performed into the expected folder. This is accomplished by extracting package contents into a project's `node_modules` folder. If the `node_modules` folder of the root project or any of its dependencies is somehow replaced with a symbolic link, it could allow Arborist to write package dependencies to any arbitrary location on the file system. Note that symbolic links contained within package artifact contents are filtered out, so another means of creating a `node_modules` symbolic link would have to be employed. 1. A `preinstall` script could replace `node_modules` with a symlink. (This is prevented by using `--ignore-scripts`.) 2. An attacker could supply the target with a git repository, instructing them to run `npm install --ignore-scripts` in the root. This may be successful, because `npm install --ignore-scripts` is typically not capable of making changes outside of the project directory, so it may be deemed safe. This is patched in @npmcli/arborist 2.8.2 which is included in npm v7.20.7 and above. For more information including workarounds please see the referenced GHSA-gmw6-94gg-2rc2.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-61
Source: CVE Program / CVE List V5
Vulnerability Title
NPM arborist 后置链接漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
NPM arborist是美国npm（NPM）公司的一个软件包。用于可视化存储为平面列表的分层数据。 NPM arborist 存在后置链接漏洞，该漏洞源于网络系统或产品的代码开发过程中存在设计或实现不当的问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
npm arborist < 2.8.2 -

II. Public POCs for CVE-2021-39135

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III. Intelligence Information for CVE-2021-39135

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Vendor Advisories for CVE-2021-39135 (3)

Same Patch Batch · npm · 2021-08-31 · 5 CVEs total

CVE-2021-37701 8.2 HIGH Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cac
CVE-2021-37712 8.2 HIGH Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cac
CVE-2021-37713 8.2 HIGH Arbitrary File Creation/Overwrite on Windows via insufficient relative path sanitization
CVE-2021-39134 8.2 HIGH UNIX Symbolic Link (Symlink) Following in @npmcli/arborist

IV. Related Vulnerabilities

Same product: arborist
Same vendor: npm
Same weakness: CWE-61

V. Comments for CVE-2021-39135

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