fix(filesystem): normalize UNC paths in access check#3601
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nielskaspers wants to merge 1 commit intomodelcontextprotocol:mainfrom
Open
fix(filesystem): normalize UNC paths in access check#3601nielskaspers wants to merge 1 commit intomodelcontextprotocol:mainfrom
nielskaspers wants to merge 1 commit intomodelcontextprotocol:mainfrom
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Use normalizePath() from path-utils instead of raw path.resolve(path.normalize()) in isPathWithinAllowedDirectories(). The normalizePath function has explicit UNC path handling that preserves the \\ prefix, whereas path.resolve can mangle UNC paths on Windows, causing subdirectory access checks to fail even when the parent UNC share is in the allowed directories list. Fixes modelcontextprotocol#3527
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Summary
UNC/network share paths (
\\server\share\subdir) fail the access check inisPathWithinAllowedDirectories()despite the parent share being in the allowed directories list. The root listing works but any subdirectory access fails.Root cause:
path-validation.tsusedpath.resolve(path.normalize(...))to normalize paths, which can mangle the\\prefix on UNC paths on Windows. Meanwhile,path-utils.tsalready has anormalizePath()function with explicit UNC path handling that preserves the prefix correctly.Fix: Use
normalizePath()frompath-utils.tsinisPathWithinAllowedDirectories()instead of rawpath.resolve(path.normalize(...)), ensuring both the requested path and allowed directories are normalized consistently for UNC paths.All 145 existing tests pass.
Fixes #3527