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Fix Path Traversal in validate_assignment via Path Normalization #1978

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Merged
brichet merged 4 commits into from
Apr 17, 2026
+7 −3
Merged

Fix Path Traversal in validate_assignment via Path Normalization #1978

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cb21dd4
Fix path traversal validate_assignment
yueyueL Jan 9, 2026
43c4041
Merge branch 'jupyter:main' into main
yueyueL Feb 27, 2026
a8c4774
refactor: use pathlib for path traversal fix
yueyueL Feb 27, 2026
49b4e74
Update nbgrader/server_extensions/validate_assignment/handlers.py
yueyueL Feb 27, 2026
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10 changes: 7 additions & 3 deletions nbgrader/server_extensions/validate_assignment/handlers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@

from tornado import web
from textwrap import dedent
from pathlib import Path

from jupyter_server.utils import url_path_join as ujoin
from jupyter_server.base.handlers import JupyterHandler
Expand Down Expand Up @@ -38,8 +39,11 @@ def load_config(self):
return app.config

def validate_notebook(self, path):
fullpath = os.path.join(self.root_dir, path)

root = Path(self.root_dir).resolve()
target = (root / path).resolve()
if not target.is_relative_to(root):
raise web.HTTPError(403, "Access denied: path outside allowed directory")
fullpath = str(target)
Comment on lines 41 to +46
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Copilot AI Feb 27, 2026

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Consider adding validation to handle edge cases where the user-supplied path might be None or empty. While these cases may be prevented by the calling code (lines 98-102), defensive programming would suggest checking for these conditions before path operations to provide clearer error messages. For example:

if not path:
    raise web.HTTPError(400, "Path parameter is required")

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try:
config = self.load_config()
validator = Validator(config=config)
Expand Down Expand Up @@ -144,4 +148,4 @@ def load_jupyter_server_extension(nbapp):
webapp.add_handlers(".*$", [
(ujoin(base_url, pat), handler)
for pat, handler in default_handlers
])
])
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