fix(runtime): decide path containment with relative(), not a string prefix - #518
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The runtime package server tested containment with
absPath.startsWith(`${nodeModulesDir}/`). The separator is hard-coded to
POSIX, so on Windows hosts, where resolve() yields backslashes, the check
was false for every legitimate path and the endpoint 404'd all runtime
package assets. It fails closed, so this is an availability bug rather
than a bypass, but the code is wrong either way.
Containment now goes through a shared isPathWithin helper that decides
with path.relative(), which is separator-correct on both platforms.
assertPathWithin delegates to it, and the '..' test compares a whole
segment so a child legitimately named '..foo' is no longer read as an
escape.
The same sweep found the inverse spelling in virtualSiteWorkspace, a
prefix check with no separator at all, which would accept a sibling
directory whose name merely begins with the root. Routed through the same
helper.
Reported as GHSA-hwp9-vc7h-gvvf.
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The bug
The runtime package server tested containment with
absPath.startsWith(${nodeModulesDir}/). The separator is hard-coded to POSIX, so on Windows hosts, whereresolve()yields backslashes, the check was false for every legitimate path and the endpoint 404'd all runtime package assets. Windows is a supported target: the release workflow ships awindows-x64server build.It fails closed, so this is an availability bug rather than a bypass. The code is wrong either way.
The fix
Containment now goes through a shared
isPathWithinhelper that decides withpath.relative(), which is separator-correct on both platforms.assertPathWithindelegates to it, and the..test compares a whole segment so a child legitimately named..foois no longer read as an escape.The same sweep found the inverse spelling in
virtualSiteWorkspace, a prefix check with no separator at all, which would accept a sibling directory whose name merely begins with the root. Routed through the same helper.Reported as GHSA-hwp9-vc7h-gvvf.
Verification
Notes
New unit tests cover the sibling-prefix and
..foocases, which are observable on POSIX. The Windows separator behaviour itself comes frompath.relative()being platform-native.