GHSA-3R68-X3XC-RXPG
Vulnerability from github – Published: 2026-05-05 20:15 – Updated: 2026-05-13 15:20Description
Impact
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.
The 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.
Affected code (src/wireshark_mcp/tshark/client.py:531-543):
output_validation = self._validate_output_path(dest_dir)
# _validate_output_path only enforces the sandbox when _allowed_dirs is set.
# Default: _allowed_dirs = None → no restriction.
os.makedirs(dest_dir, exist_ok=True) # creates arbitrary directories
cmd = [..., "--export-objects", f"{protocol},{dest_dir}"]
Attack Scenario
An 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:
dest_dir=/home/user/.ssh/
tshark then extracts and writes the HTTP object to that path, granting the attacker SSH access.
The same technique can target:
-
/etc/cron.d/ -
Writable web roots
-
Other sensitive filesystem locations
Additional Affected Operations
The same missing sandbox affects:
-
merge_pcap_files -
editcap_trim -
editcap_split -
editcap_time_shift -
editcap_deduplicate -
text2pcap_import
Proof of Concept
Confirmed on wireshark-mcp v1.1.5 with tshark 4.6.4.
A crafted pcap’s HTTP object was successfully written to an arbitrary filesystem path when:
_allowed_dirs = None
Patches
Not yet patched.
A fix should make the path sandbox mandatory for all file-write operations rather than optional:
# Reject all write operations when no sandbox is configured
if not self._allowed_dirs:
return json.dumps({
"success": False,
"error": {
"type": "SecurityError",
"message": "Set WIRESHARK_MCP_ALLOWED_DIRS before using file-write operations"
}
})
Workarounds
Set WIRESHARK_MCP_ALLOWED_DIRS to a restricted safe directory before starting the server:
export WIRESHARK_MCP_ALLOWED_DIRS=/tmp/wireshark_mcp_safe
This activates the existing sandbox and blocks writes outside the allowed path.
Resources
-
Vulnerable code:
-
src/wireshark_mcp/tshark/client.pylines 521–543 -
src/wireshark_mcp/tshark/client.pylines 685–839 -
CWE-22: Improper Limitation of a Pathname to a Restricted Directory
-
CWE-73: External Control of File Name or Path
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "wireshark-mcp"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "1.1.5"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-43901"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-05T20:15:12Z",
"nvd_published_at": "2026-05-11T23:20:21Z",
"severity": "MODERATE"
},
"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\u0027s `--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 \u2192 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\u2019s 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\u2013543\n\n - `src/wireshark_mcp/tshark/client.py` lines 685\u2013839\n\n- CWE-22: Improper Limitation of a Pathname to a Restricted Directory\n\n- CWE-73: External Control of File Name or Path",
"id": "GHSA-3r68-x3xc-rxpg",
"modified": "2026-05-13T15:20:15Z",
"published": "2026-05-05T20:15:12Z",
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "wireshark-mcp vulnerable to arbitrary file write via export_objects when WIRESHARK_MCP_ALLOWED_DIRS is not configured"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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