fix(storage): block path traversal in file-download (GHSA-6px9-99p6-7j7g, 0.60.1) - #409
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`storage file-download` wrote the downloaded bytes to the Storage API's `file_detail["name"]` verbatim when --output was omitted. A malicious or compromised API response (e.g. a file in a shared/invited project) with a name like `../../../../.zshrc` -- or an absolute path -- could overwrite an arbitrary file on the user's machine with attacker-controlled content, a clean write-to-RCE primitive. Add `_safe_download_target()`: strip leading separators (an absolute name can no longer override the target), preserve legitimate nested subpaths, and assert the resolved path stays within the chosen directory (CWD or the --output dir) via resolve() + is_relative_to(), rejecting escapes with INVALID_ARGUMENT. Explicit `--output FILE` is unchanged (trusted user input). Private advisory GHSA-6px9-99p6-7j7g.
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Summary
Fixes a path-traversal arbitrary-file-write in
kbagent storage file-download— finding H2 from the 2026-06-12 security audit (private advisory GHSA-6px9-99p6-7j7g).When
--outputwas omitted, the downloaded bytes were written to the Storage API'sfile_detail["name"]verbatim (storage_service.py:1746/1770→client.download_filewhich doesout_path.parent.mkdir(parents=True)). A malicious or compromised API response (e.g. a file in a shared/invited project, wherenamelabels are loosely constrained) with a name like../../../../.zshrc— or an absolute path like/Users/victim/Library/LaunchAgents/x.plist— could overwrite an arbitrary file on the user's machine with fully attacker-controlled content. A clean write-to-RCE primitive.Fix
New
_safe_download_target(base, server_name)helper instorage_service:exports/2026/report.csvstill creates the subdir, as before);--outputdirectory) viaresolve()+is_relative_to(), rejecting escapes withINVALID_ARGUMENT.Explicit
--output FILEis unchanged — it is the user's own trusted choice. For honest file names behavior is identical to before; only..// absolute escapes are blocked, so no regression for legitimate use.Tests
New
TestDownloadFilePathTraversal(4 cases): rejects../escape with and without an--outputdirectory, neutralizes absolute names under CWD, and preserves benign nested names. Full suite green: 3959 passed, 132 skipped; lint/format/ty/changelog-check clean.Audit context
The other HIGH finding (auto-update artifact integrity, GHSA-3322-j9h9-mg9p) was accepted as residual risk by the repo owner (GitHub as trust root; silent auto-update retained as the patch-delivery channel) and closed won't-fix. The remaining MEDIUM/LOW advisories stay open as draft for separate triage.