id: PYSEC-2026-3426
published: "2026-07-13T15:15:37.943032Z"
modified: "2026-07-13T16:07:33.645438Z"
aliases:
- CVE-2026-43901
- GHSA-3r68-x3xc-rxpg
summary: wireshark-mcp vulnerable to arbitrary file write via export_objects when WIRESHARK_MCP_ALLOWED_DIRS is not configured
details: "## Description\n\n### Impact\n\n`wireshark-mcp` exposes a `wireshark_export_objects` MCP tool that accepts an attacker-controlled `dest_dir` parameter and passes it to tshark's `--export-objects` flag with **no mandatory path restriction**.\n\nThe path sandbox (`_allowed_dirs`) is `None` by default and only activates when the environment variable `WIRESHARK_MCP_ALLOWED_DIRS` is explicitly set. In a default installation, any directory on the filesystem can be used as the export destination.\n\n**Affected code** (`src/wireshark_mcp/tshark/client.py:531-543`):\n\n```python\n\noutput_validation = self._validate_output_path(dest_dir)\n\n# _validate_output_path only enforces the sandbox when _allowed_dirs is set.\n\n# Default: _allowed_dirs = None → no restriction.\n\nos.makedirs(dest_dir, exist_ok=True)   # creates arbitrary directories\n\ncmd = [..., \"--export-objects\", f\"{protocol},{dest_dir}\"]\n\n```\n\n### Attack Scenario\n\nAn attacker embeds a crafted HTTP response in a pcap file (e.g. `Content-Disposition: filename=authorized_keys`). Via prompt injection in the pcap payload, an AI model using this MCP server is manipulated into calling `wireshark_export_objects` with:\n\n```bash\n\ndest_dir=/home/user/.ssh/\n\n```\n\n`tshark` then extracts and writes the HTTP object to that path, granting the attacker SSH access.\n\nThe same technique can target:\n\n- `/etc/cron.d/`\n\n- Writable web roots\n\n- Other sensitive filesystem locations\n\n### Additional Affected Operations\n\nThe same missing sandbox affects:\n\n- `merge_pcap_files`\n\n- `editcap_trim`\n\n- `editcap_split`\n\n- `editcap_time_shift`\n\n- `editcap_deduplicate`\n\n- `text2pcap_import`\n\n### Proof of Concept\n\nConfirmed on **wireshark-mcp v1.1.5** with **tshark 4.6.4**.\n\nA crafted pcap’s HTTP object was successfully written to an arbitrary filesystem path when:\n\n```python\n\n_allowed_dirs = None\n\n```\n\n---\n\n## Patches\n\nNot yet patched.\n\nA fix should make the path sandbox **mandatory** for all file-write operations rather than optional:\n\n```python\n\n# Reject all write operations when no sandbox is configured\n\nif not self._allowed_dirs:\n\n    return json.dumps({\n\n        \"success\": False,\n\n        \"error\": {\n\n            \"type\": \"SecurityError\",\n\n            \"message\": \"Set WIRESHARK_MCP_ALLOWED_DIRS before using file-write operations\"\n\n        }\n\n    })\n\n```\n\n---\n\n## Workarounds\n\nSet `WIRESHARK_MCP_ALLOWED_DIRS` to a restricted safe directory before starting the server:\n\n```bash\n\nexport WIRESHARK_MCP_ALLOWED_DIRS=/tmp/wireshark_mcp_safe\n\n```\n\nThis activates the existing sandbox and blocks writes outside the allowed path.\n\n---\n\n## Resources\n\n- Vulnerable code:\n\n  - `src/wireshark_mcp/tshark/client.py` lines 521–543\n\n  - `src/wireshark_mcp/tshark/client.py` lines 685–839\n\n- CWE-22: Improper Limitation of a Pathname to a Restricted Directory\n\n- CWE-73: External Control of File Name or Path"
affected:
- package:
    name: wireshark-mcp
    ecosystem: PyPI
    purl: pkg:pypi/wireshark-mcp
  ranges:
  - type: ECOSYSTEM
    events:
    - introduced: "0"
    - last_affected: 1.1.5
  versions:
  - 0.2.1
  - 0.4.0
  - 0.5.0
  - 0.6.0
  - 0.6.1
  - 0.6.2
  - 0.6.3
  - 0.6.4
  - 0.6.5
  - 1.0.0
  - 1.1.0
  - 1.1.5
references:
- type: WEB
  url: https://github.com/bx33661/Wireshark-MCP/security/advisories/GHSA-3r68-x3xc-rxpg
- type: ADVISORY
  url: https://nvd.nist.gov/vuln/detail/CVE-2026-43901
- type: PACKAGE
  url: https://github.com/bx33661/Wireshark-MCP
- type: PACKAGE
  url: https://pypi.org/project/wireshark-mcp
- type: ADVISORY
  url: https://github.com/advisories/GHSA-3r68-x3xc-rxpg
severity:
- type: CVSS_V3
  score: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N