EUVD-2026-19537

Description

# Zip Slip Path Traversal in coder/code-marketplace ## Summary A Zip Slip (CWE-22) vulnerability in `coder/code-marketplace` ≤ v2.4.1 allowed a malicious VSIX file to write arbitrary files outside the extension directory. `ExtractZip` passed raw zip entry names to a callback that wrote files via `filepath.Join` with no boundary check; `filepath.Join` resolved `..` components but did not prevent the result from escaping the base path. ## Root Cause `ExtractZip` passed the raw, attacker-controlled `zf.Name` to a caller-supplied callback: ```go return false, fn(zf.Name, zr) // zf.Name not sanitized ``` `AddExtension` constructed the output path with `filepath.Join` and no boundary check: ```go path := filepath.Join(dir, name) // zip loop path := filepath.Join(dir, file.RelativePath) // extra files loop ``` `filepath.Clean` resolved `..` lexically but did not confine the result to `dir`: ``` filepath.Join("/srv/ext/pub/1.0", "../../../../etc/cron.d/evil") → "/etc/cron.d/evil" ``` ## Attack Scenario An authenticated user (any upload-capable role) would submit a VSIX containing path-traversal entries. On extraction, files would land at attacker-chosen paths writable by the marketplace process, enabling persistence (cron/init injection), SSH key injection, `ld.so.preload` hijacking, or binary overwrite depending on process privileges. ## Fix Addressed in https://github.com/coder/code-marketplace/releases/tag/v2.4.2 ## Recognition Coder would like to thank [Kandlaguduru Vamsi](https://www.linkedin.com/in/vamsi-k-5419632a9/) for responsibly disclosing this issue in accordance with https://coder.com/security/policy

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