tarproject tar CVE-2021-32803 vulnerability in Tarproject and Other Products
Published on August 3, 2021

Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning

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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.

Github Repository NVD

Vulnerability Analysis

CVE-2021-32803 can be exploited with local system access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality and integrity, and no impact on availability.

Attack Vector:
LOCAL
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
REQUIRED
Scope:
CHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
HIGH
Availability Impact:
NONE

Weakness Type

What is a Directory traversal Vulnerability?

The software uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

CVE-2021-32803 has been classified to as a Directory traversal vulnerability or weakness.


Products Associated with CVE-2021-32803

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2021-32803 are published in these products:

Tarproject Tar
 
Oracle GraalVM
 
Siemens Sinec Infrastructure Network Services
 

Affected Versions

npm node-tar:

Vulnerable Packages

The following package name and versions may be associated with CVE-2021-32803

Package Manager Vulnerable Package Versions Fixed In
npm tar >= 4.0.0, < 4.4.15 4.4.15
npm tar >= 5.0.0, < 5.0.7 5.0.7
npm tar < 3.2.3 3.2.3
npm tar >= 6.0.0, < 6.1.2 6.1.2
npm tar >= 6.0.0, < 6.1.1 6.1.1
npm tar >= 5.0.0, < 5.0.6 5.0.6
npm tar >= 4.0.0, < 4.4.14 4.4.14
npm tar < 3.2.2 3.2.2

Exploit Probability

EPSS
0.15%
Percentile
35.20%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.