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Fix tarfile symlink/hardlink escape in safe_extract #45

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Merged
rilma merged 2 commits into from
Feb 21, 2026
Merged

Fix tarfile symlink/hardlink escape in safe_extract #45

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Copilot Feb 21, 2026
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Fix tarfile symlink/hardlink escape vulnerability in safe_extract
Copilot Feb 21, 2026
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15 changes: 13 additions & 2 deletions pyiri2016/api/update.py
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Original file line number Diff line number Diff line change
Expand Up @@ -18,14 +18,25 @@ def is_within_directory(base_dir, target):
except ValueError:
return False

def safe_extract(tar, path=".", members=None, *, numeric_owner=False):
def safe_extract(tar, path=".", *, numeric_owner=False):

# Use the built-in extraction filter when available (Python >=3.11.4 / >=3.12)
if hasattr(tarfile, "data_filter"):
tar.extractall(path, numeric_owner=numeric_owner, filter=tarfile.data_filter)
return

safe_members = []
for member in tar.getmembers():
# Reject symlinks, hardlinks and special files to prevent
# escape-via-link attacks even when the path looks safe.
if member.issym() or member.islnk() or member.isdev():
raise ValueError(f"Unsafe tar member type: {member.name}")
member_path = os.path.join(path, member.name)
if not is_within_directory(path, member_path):
raise ValueError("Attempted Path Traversal in Tar File")
safe_members.append(member)

tar.extractall(path, members, numeric_owner=numeric_owner)
tar.extractall(path, safe_members, numeric_owner=numeric_owner)

safe_extract(tar, path=directory)
os.remove(retrieved_fullpath)