CVE-2026-39246: decompress — Exploit & Fix

Description

decompress before 4.2.2 allows arbitrary symlink creation during archive extraction. When processing symlink entries (type === 'symlink'), the x.linkname field from the archive is passed directly to fs.symlink() without validation (index.js line 121). The preventWritingThroughSymlink check on line 98 only applies to file entries, not symlink creation. An attacker can craft an archive with symlink entries pointing to sensitive files outside the extraction directory (e.g., /etc/passwd), enabling information disclosure when the application reads the extracted contents.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS — Exploit Prediction

0.0050

Probability of exploitation

0.40%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-59 CWE-59

Affected Products

Vendor	Product	Versions
decompress_project	decompress	< 4.2.1

References

Advisories & Patches

https://github.com/kevva/decompress/issues/114 https://github.com/kevva/decompress/issues/114

Exploits

https://github.com/kevva/decompress/issues/114 https://github.com/kevva/decompress/issues/114

Other References

https://github.com/kevva/decompress https://www.npmjs.com/package/decompress

Frequently Asked Questions

What is CVE-2026-39246? +

decompress before 4.2.2 allows arbitrary symlink creation during archive extraction. When processing symlink entries (type === 'symlink'), the x.linkname field from the archive is passed directly to fs.symlink() without validation (index.js line 121). The preventWritingThroughSymlink check on line 98 only applies to file entries, not symlink creation. An attacker can craft an archive with symlink entries pointing to sensitive files outside the extraction directory (e.g., /etc/passwd), enabling information disclosure when the application reads the extracted contents. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-39246? +

CVE-2026-39246 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0050, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-39246? +

CVE-2026-39246 affects products from decompress_project, specifically: decompress. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-39246? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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