8.2

CVSS Score

4.0

-

CVSS Score

Basic Information

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CVE-2026-23745

CVE-2026-23745: node-tar Vulnerable to Arbitrary File Overwrite and Symlink Poisoning via Insufficient Path Sanitization

node-tar is a Tar for Node.js. The node-tar library (<= 7.5.2) fails to sanitize the linkpath of Link (hardlink) and SymbolicLink entries when preservePaths is false (the default secure behavior). This allows malicious archives to bypass the extraction root restriction, leading to Arbitrary File Overwrite via hardlinks and Symlink Poisoning via absolute symlink targets. This vulnerability is fixed in 7.5.3.

(GitHub Advisory)

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CVE-2026-23745

CVE-2026-23745:

8.2

CVSS Score

4.0

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
tar	npm	<= 7.5.2	7.5.3

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability in node-tar allows for arbitrary file overwrite and symlink poisoning. The root cause is the insufficient sanitization of the linkpath field for hardlink and symlink entries in a TAR archive. The analysis of the provided patch 340eb285b6d986e91969a1170d7fe9b0face405e confirms this. The patch introduces a new sanitization method, [STRIPABSOLUTEPATH], and applies it to both the path and linkpath properties of an entry within the [CHECKPATH] method. Before this fix, only the path property was being sanitized.

This lack of validation on the linkpath made the following functions vulnerable:

Unpack[HARDLINK]: This method would use the unsanitized linkpath to create a hardlink. A malicious actor could provide an absolute path, causing the hardlink to point to a sensitive file outside of the intended extraction directory. Subsequent writes would then modify the targeted system file.
Unpack[SYMLINK]: This method would use the unsanitized linkpath as the target for a symbolic link. This could be an absolute path or contain directory traversal characters (../), allowing an attacker to create a symlink pointing anywhere on the filesystem.

The function Unpack[CHECKPATH] is also identified as vulnerable because its pre-patch implementation contained the flaw (the omission of linkpath sanitization) that enabled the exploit. The exploit itself, however, would be triggered within the [HARDLINK] and [SYMLINK] methods, which perform the file system operations.

Vulnerable functions

Unpack[HARDLINK]

src/unpack.ts

The `[HARDLINK]` method processes hardlink entries from a TAR archive. It uses the `entry.linkpath` property to determine the target file for the hardlink. The vulnerability exists because this `linkpath` was not sanitized. An attacker could craft a TAR file with a hardlink entry where the `linkpath` is an absolute path to a sensitive file on the system (e.g., '/etc/passwd'). When `node-tar` extracts this, it would create a hardlink to that system file within the extraction directory. If the extraction process subsequently writes to this file, it would overwrite the original sensitive file, leading to arbitrary file overwrite.

Unpack[SYMLINK]

src/unpack.ts

The `[SYMLINK]` method processes symbolic link entries. It uses the `entry.linkpath` from the TAR entry as the target for the symbolic link. The vulnerability is that this path was passed directly to the `fs.symlink` function without validation. This allows an attacker to create a TAR file with a symlink entry pointing to an absolute path (e.g., '/etc/shadow') or using directory traversal (`../../`). This results in the creation of a symbolic link pointing outside the intended extraction directory, a vulnerability known as symlink poisoning.

Unpack[CHECKPATH]

src/unpack.ts

The `[CHECKPATH]` function is responsible for validating tar entries before extraction. The vulnerability existed in the pre-patch version of this function because it only sanitized the `entry.path` field and completely neglected to sanitize the `entry.linkpath` field. This oversight allowed malicious `linkpath` values to be passed to the `[HARDLINK]` and `[SYMLINK]` methods, leading to the file overwrite and symlink poisoning vulnerabilities.

Vulnerability Intelligence
Miggo AI

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WAF Protection Rules

WAF Rule

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Reasoning

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