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CVE-2021-32803— Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning

Quick assessment

Affected
npm node-tar
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

node-tar是一款用于文件压缩/解压缩的软件包。 node-tar 存在后置链接漏洞，该漏洞源于符号链接保护不足而具有任意文件创建/覆盖漏洞。

CVSS 8.2 · High EPSS 7.80% · P95

Possible ATT&CK Techniques 1 AI

T1030 · Data Transfer Size Limits
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I. Basic Information for CVE-2021-32803

Vulnerability Information
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Vulnerability Title
Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning
Source: CVE Program / CVE List V5
Vulnerability Description
The npm package "tar" (aka node-tar) before versions 6.1.2, 5.0.7, 4.4.15, and 3.2.3 has an arbitrary File Creation/Overwrite vulnerability via insufficient symlink protection. `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. This order of operations resulted in the directory being created and added to the `node-tar` directory cache. When a directory is present in the directory cache, subsequent calls to mkdir for that directory are skipped. However, this is also where `node-tar` checks for symlinks occur. By first creating a directory, and then replacing that directory with a symlink, it was thus possible to bypass `node-tar` symlink checks on directories, essentially allowing an untrusted tar file to symlink into an arbitrary location and subsequently extracting arbitrary files into that location, thus allowing arbitrary file creation and overwrite. This issue was addressed in releases 3.2.3, 4.4.15, 5.0.7 and 6.1.2.
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
对路径名的限制不恰当(路径遍历)
Source: CVE Program / CVE List V5
Vulnerability Title
node-tar 后置链接漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
node-tar是一款用于文件压缩/解压缩的软件包。 node-tar 存在后置链接漏洞，该漏洞源于符号链接保护不足而具有任意文件创建/覆盖漏洞。
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 node-tar < 3.2.3 -

II. Public POCs for CVE-2021-32803

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 8070 chars
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III. Intelligence Information for CVE-2021-32803

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Patches & Fixes for CVE-2021-32803 (1)

Vendor Advisories for CVE-2021-32803 (3)

Other References for CVE-2021-32803 (2)

IV. Related Vulnerabilities

Same product: node-tar
Same vendor: npm
Same weakness: CWE-22

V. Comments for CVE-2021-32803

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