🛡️ Sentinel: [HIGH] Fix Zip Slip in Addon Export by anchapin · Pull Request #524 · anchapin/ModPorter-AI

anchapin · 2026-02-18T00:33:07Z

Fixed a High/Critical Zip Slip vulnerability in the addon export functionality. Maliciously crafted asset filenames could lead to path traversal when the exported archive is extracted.

Changes:

Added _sanitize_filename helper in addon_exporter.py.
Sanitized original_filename for all assets before adding to ZIP.
Ensured consistent naming in generated JSON manifests.
Added unit test test_addon_exporter_security.py to verify the fix.

PR created automatically by Jules for task 17170767585595288513 started by @anchapin

google-labs-jules · 2026-02-18T00:33:08Z

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Pull request overview

This PR aims to harden the backend’s addon export pipeline against Zip Slip (path traversal) by sanitizing asset filenames before writing them into the exported .mcaddon (ZIP) and aligning generated JSON naming with sanitized values.

Changes:

Added a _sanitize_filename helper and applied it to asset filenames used for ZIP entry paths.
Updated texture/sound naming derivation in generated JSON to use sanitized filenames.
Added a unit test to assert exported ZIPs don’t contain traversal paths.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
`backend/src/services/addon_exporter.py`	Introduces filename sanitization and applies it when generating ZIP entry paths and JSON-derived names.
`backend/src/tests/unit/test_addon_exporter_security.py`	Adds a regression test intended to catch Zip Slip attempts during mcaddon creation.
`.jules/sentinel.md`	Documents the Zip Slip learning/prevention guidance for future Sentinel runs.

Copilot · 2026-02-18T00:41:03Z

backend/src/services/addon_exporter.py

+    filename = "".join(c for c in filename if c.isalnum() or c in "._-")
+    # Ensure not empty
+    if not filename:
+        return "default_sanitized_filename"


_sanitize_filename still allows dangerous path segments like . and .. because dots are allowlisted. If filename is .. (or sanitizes down to ..), os.path.join(..., "..") will produce ZIP entries containing ../ after normalization by many extractors, so Zip Slip is still possible. Consider explicitly rejecting ./.. (and optionally any name that becomes only dots) after sanitization and falling back to a safe generated name.

Suggested change

return "default_sanitized_filename"

return "default_sanitized_filename"

# Reject filenames that are only dots (e.g. ".", "..", "...")

if all(c == "." for c in filename):

return f"default_sanitized_{uuid.uuid4().hex}"

Copilot · 2026-02-18T00:41:04Z

backend/src/services/addon_exporter.py

            # or we derive from original_filename.

-            texture_name = os.path.splitext(asset.original_filename)[0] if asset.original_filename else \
-                           os.path.splitext(os.path.basename(asset.path))[0]
+            original_name = _sanitize_filename(asset.original_filename) if asset.original_filename else \
+                            _sanitize_filename(os.path.basename(asset.path))
+            texture_name = os.path.splitext(original_name)[0]


generate_terrain_texture_json is called with texture_assets = [asset for asset in addon_pydantic.assets if asset.type.startswith("texture")] (so it includes texture_block / texture_item), but this function still only processes assets where asset.type == "texture". As a result, terrain_texture.json will likely be generated with an empty texture_data for most real texture assets. Updating the condition to match the caller’s selection (e.g., startswith("texture") or handling the texture_* variants) should fix this.

Copilot · 2026-02-18T00:41:04Z

backend/src/tests/unit/test_addon_exporter_security.py

+    # Malicious filename attempting traversal
+    malicious_filename = "../../../../malicious.txt"
+


The test only covers a traversal attempt using ../../.. in the filename. Since _sanitize_filename currently allowlists dots, a filename like .. (or one that sanitizes down to ..) would be a more direct regression case to add here, because it can still introduce .. path segments into ZIP entry names.

- Implemented `_sanitize_filename` in `backend/src/services/addon_exporter.py` to strip directory paths and restrict characters to alphanumeric, `.`, `_`, `-`. - Applied sanitization to all asset types (textures, sounds, models, entities) in `create_mcaddon_zip`. - Updated JSON manifest generation (`terrain_texture.json`, `sounds.json`) to use sanitized filenames for consistency. - Added regression test `backend/src/tests/unit/test_addon_exporter_security.py` demonstrating the vulnerability prevention. This prevents malicious filenames (e.g., `../../file`) from being included in exported mcaddon/zip files, which could lead to arbitrary file writes upon extraction. Co-authored-by: anchapin <6326294+anchapin@users.noreply.github.com>

- Resolved `ModuleNotFoundError: No module named 'ai_engine'` in CI by correcting import paths in `ai-engine/tests/`. Removed `ai_engine.` prefix as the package root is `ai-engine/` and tests run from there. - Fixed `_calculate_load_order` in `mod_dependency_analyzer.py` to correctly order dependencies before dependents (topological sort was using in-degree instead of out-degree logic). - Updated `KNOWN_CONFLICTS` in `modpack_conflict_detector.py` to correctly identify conflicts between JEI and REI by adding aliases. - Verified all affected tests pass locally. Co-authored-by: anchapin <6326294+anchapin@users.noreply.github.com>

…pload.tsx - Removed unnecessary escape characters in regex patterns in `frontend/src/utils/urlParser.ts` to fix ESLint errors (`no-useless-escape`). - Fixed a syntax error in `frontend/src/components/ConversionUpload/ConversionUpload.tsx` where a `)` was missing in a `getPlatformInfo` call. - Installed missing dev dependency `eslint-plugin-storybook` to enable linting locally. - Verified linting passes with `npm run lint`. Co-authored-by: anchapin <6326294+anchapin@users.noreply.github.com>

Copilot AI review requested due to automatic review settings February 18, 2026 00:33

sourcery-ai bot reviewed Feb 18, 2026

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Copilot started reviewing on behalf of anchapin February 18, 2026 00:33 View session

Copilot AI reviewed Feb 18, 2026

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google-labs-jules bot and others added 3 commits February 17, 2026 21:25

anchapin force-pushed the sentinel-fix-zip-slip-addon-export-17170767585595288513 branch from 985fee7 to de1bb10 Compare February 18, 2026 02:27

anchapin merged commit 63317ea into main Feb 18, 2026
6 of 7 checks passed

anchapin deleted the sentinel-fix-zip-slip-addon-export-17170767585595288513 branch February 18, 2026 02:27

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🛡️ Sentinel: [HIGH] Fix Zip Slip in Addon Export#524

🛡️ Sentinel: [HIGH] Fix Zip Slip in Addon Export#524
anchapin merged 3 commits intomainfrom
sentinel-fix-zip-slip-addon-export-17170767585595288513

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-        return "default_sanitized_filename"
+        return "default_sanitized_filename"
+    # Reject filenames that are only dots (e.g. ".", "..", "...")
+    if all(c == "." for c in filename):
+        return f"default_sanitized_{uuid.uuid4().hex}"

		# Malicious filename attempting traversal
		malicious_filename = "../../../../malicious.txt"

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