CVE-2026-39243

What it is

decompress before 4.2.2 allows arbitrary hardlink creation during archive extraction, enabling file read disclosure and file corruption. When processing hardlink entries (type === 'link'), the x.linkname field from the archive is passed directly to fs.link() without validation (index.js line 113). An attacker can craft an archive with a hardlink entry whose linkname is an absolute path to any file on the same filesystem. This creates a hardlink inside the extraction directory that shares the same inode as the target file, enabling both reading and overwriting the original file's content. Hardlinks are limited to files on the same filesystem and cannot target directories.

At a glance

Exploitability

Can be exploited locally on the machine without logging in, but needs a user to act. High risk of data exposure.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-09 22:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-13 12:57 UTC Last updatedMost recent change to the record

Details

Published

2026-07-09 22:17 UTC

Last modified

2026-07-13 12:57 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-59

Record status

Analyzed

Affected

• Decompress Project Decompress ≤ 4.2.1

Attack profile CVSS 3.1 · 5.5

Attack vector

Local

Complexity

Low

Privileges needed

None

User interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None