CVE-2026-39243: decompress_project decompress

Vulnerability summary

CVE-2026-39243 is a medium (CVSS 5.5) vulnerability in decompress_project decompress. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 22.9% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 09-07-2026
   PublishedVulnerability first disclosed.
2. 10-07-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-59Improper Link Resolution Before File AccessThe product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.