Vulnerability in Decompress Project
CVE-2026-39243
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.003 (21.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 21.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
Weakness classification (CWE)
References
- github.com/kevva/decompress (Product)
- www.npmjs.com/package/decompress (Product)
- github.com/kevva/decompress/issues/113 (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-39243?
- CVE-2026-39243 is a medium-severity vulnerability in Decompress Project, classified under Improper Link Resolution Before File Access. CVSS score: 5.5/10. Published 2026-07-09.
- How severe is CVE-2026-39243?
- Medium severity. CVSS v3 base score is 5.5 out of 10.