fix: reject zip-slip / path-traversal entries in extractTarball#22
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fix: reject zip-slip / path-traversal entries in extractTarball#22
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`tar.extract({ strip: 1 })` on an attacker-controlled tarball will happily
write `../../etc/passwd` if the entry path escapes cwd after the strip.
Add an explicit `filter` predicate that rejects:
- empty paths
- absolute paths (POSIX leading `/`)
- Windows drive-letter paths ("C:foo", "C:\\…")
- entries that normalize to something starting with `..` (escapes cwd)
The first rejected entry is captured and surfaced as a `DownloadError`
with a new `UNSAFE_ENTRY` code, instead of `filter` silently skipping it.
Tests: `isSafeTarEntry` is now exported and covered with safe + unsafe
cases including a regression check that mid-path `..` segments which
collapse back inside cwd are still accepted.
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From the 2026-05-01 audit (P1.4):
tar.extract({ strip: 1 })had nofilter— a hostile or corrupt tarball entry like../../etc/passwdwould extract outside the destination directory.Fix
isSafeTarEntry()predicate (exported) that rejects empty, absolute (POSIX), Windows drive-letter, and..-escape paths.filtercallback inextractTarballconsults the predicate.DownloadErrorcodeUNSAFE_ENTRY...that collapses back inside cwd.Test plan