CVE-2026-39245
decompress Directory Traversal and Arbitrary File Write Vulnerability
Description
decompress before 4.2.2 contains an improper path containment check that enables directory traversal and arbitrary file write. The safeMakeDir function (index.js line 29) and the extraction path validation (index.js line 106) use String.indexOf() to verify the resolved path is within the output directory: realDestinationDir.indexOf(realOutputPath) !== 0. This check is flawed because it does not enforce a path separator boundary. For example, "/tmp/app_config".indexOf("/tmp/app") returns 0, incorrectly passing the check even though /tmp/app_config is outside /tmp/app. Combined with the unvalidated symlink creation in the same package, an attacker can write arbitrary files to directories adjacent to the extraction target. This is a bypass of the fix for CVE-2020-12265. The correct check requires appending a path separator: realParentPath.indexOf(realOutputPath + path.sep) !== 0.
INFO
Published Date :
July 9, 2026, 10:17 p.m.
Last Modified :
July 13, 2026, 12:56 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update the decompress package to version 4.2.2 or later.
- Ensure path validation includes path separators.
- Validate symlink creation during extraction.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-39245.
| URL | Resource |
|---|---|
| https://github.com/kevva/decompress | Product |
| https://github.com/kevva/decompress/issues/115 | Exploit Vendor Advisory |
| https://nvd.nist.gov/vuln/detail/CVE-2020-12265 | US Government Resource |
| https://www.npmjs.com/package/decompress | Product |
| https://github.com/kevva/decompress/issues/115 | Exploit Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-39245 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-39245
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-39245 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-39245 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 13, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:decompress_project:decompress:*:*:*:*:*:node.js:*:* versions up to (including) 4.2.1 Added Reference Type MITRE: https://github.com/kevva/decompress Types: Product Added Reference Type MITRE: https://github.com/kevva/decompress/issues/115 Types: Exploit, Vendor Advisory Added Reference Type MITRE: https://nvd.nist.gov/vuln/detail/CVE-2020-12265 Types: US Government Resource Added Reference Type MITRE: https://www.npmjs.com/package/decompress Types: Product Added Reference Type CISA-ADP: https://github.com/kevva/decompress/issues/115 Types: Exploit, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 10, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Added CWE CWE-22 Added Reference https://github.com/kevva/decompress/issues/115 Added SSVC {'id': 'CVE-2026-39245', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-10T15:19:01.067636Z'} -
New CVE Received by [email protected]
Jul. 09, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'n/a', 'product': 'n/a', 'versions': [{'status': 'affected', 'version': 'n/a'}]}] Added Description decompress before 4.2.2 contains an improper path containment check that enables directory traversal and arbitrary file write. The safeMakeDir function (index.js line 29) and the extraction path validation (index.js line 106) use String.indexOf() to verify the resolved path is within the output directory: realDestinationDir.indexOf(realOutputPath) !== 0. This check is flawed because it does not enforce a path separator boundary. For example, "/tmp/app_config".indexOf("/tmp/app") returns 0, incorrectly passing the check even though /tmp/app_config is outside /tmp/app. Combined with the unvalidated symlink creation in the same package, an attacker can write arbitrary files to directories adjacent to the extraction target. This is a bypass of the fix for CVE-2020-12265. The correct check requires appending a path separator: realParentPath.indexOf(realOutputPath + path.sep) !== 0. Added Reference https://github.com/kevva/decompress Added Reference https://github.com/kevva/decompress/issues/115 Added Reference https://nvd.nist.gov/vuln/detail/CVE-2020-12265 Added Reference https://www.npmjs.com/package/decompress