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This study investigates the implications of file-level copying in the open-source ecosystem, revealing that such practices obscure critical dependency signals like provenance and security. Analyzing a sample of 690,500 copy events, the authors identify 13 distinct copy forms, highlighting that many copied sources are outdated and lack traceable origins, which poses significant security and compliance risks. The findings indicate that security vulnerabilities are predominantly found in vendored dependencies, with a concerning percentage of high-risk copies lacking upstream fixes, emphasizing the need for better governance in software reuse.
File-level copying in open source obscures vital dependency signals, leading to significant security and compliance risks that are often invisible to current dependency scanners.
File-level copying is a widespread but ungoverned form of software reuse. Copying files across repositories reduces supply-chain visibility: it removes the four observable signals a package manager provides for a declared dependency (provenance, maintenance, security, and compliance) with no mechanism to restore them. To characterize the scale and consequences of this unmanaged reuse, we present a mixed-method study of copying across the entire open-source ecosystem using World of Code (WoC). From a 0.1% commit sample, we extract 690,500 copy events and retain 3,912 rationale-bearing copy commits for intent labeling. We show that the 13 axial copy forms, spanning vendored dependencies, hardware/driver synchronization, scaffolding, UI assets, and direct source-code reuse, are unreliable proxies for developer intent: among rationale-bearing commits, hardware/driver copies are predominantly fork-maintenance work (78%), while dependency-vendoring copies more often signal upstream bypass (70%) than offline availability. These visibility gaps are form-specific: security and license risk concentrate in complementary copy forms. Copied sources are frequently stale (median 155 days; 38.5% over one year old) and seldom record a recoverable origin (4.3% documented), let alone a checkable version (2.0% versioned); even vendored copies record where they came from only 10% of the time. Security risk concentrates in vendored dependencies: 17,314 CVE-risk copy commits in the full-WoC graph, 88% in the dependency-vendoring form; 80% score CVSS>= 7.0 and upstream-fix adoption is only 47%-84%. License risk concentrates in direct source-code reuse: 41,777 pre-validation candidates, 66% in the source-code form, with 39 verified high-star violations (kappa = 0.752). Both risks reach packaged software and are invisible to dependency scanners operating on declared metadata alone.
