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.
Metrics
Affected Vendors & Products
References
History
Thu, 09 Jul 2026 22:45:00 +0000
| Type | Values Removed | Values Added |
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| First Time appeared |
Kevva
Kevva decompress |
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| Vendors & Products |
Kevva
Kevva decompress |
Thu, 09 Jul 2026 21:45:00 +0000
| Type | Values Removed | Values 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. | |
| References |
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Status: PUBLISHED
Assigner: mitre
Published:
Updated: 2026-07-09T21:33:19.574Z
Reserved: 2026-04-06T00:00:00.000Z
Link: CVE-2026-39245
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OpenCVE Enrichment
Updated: 2026-07-09T22:30:05Z