CVE-2026-49986

The Cortex MCP server (neuro-cortex-memory), a cross-platform persistent memory MCP, prior to version 3.17.1 treats the CLAUDE_PROJECT_DIR environment variable — automatically set by Claude Code to the currently open project directory — as a trusted Cortex developer checkout. When the open_visualization tool is invoked, _find_dev_source() resolves the user's active project directory as a candidate Cortex source root. The only validation performed by _is_cortex_root() is a check for the presence of an mcp_server/ subdirectory and a ui/unified-viz.html file. An attacker who places these two marker files in a malicious repository can cause Cortex to execute an arbitrary mcp_server/server/visualize_bootstrap.py from that directory via subprocess.run([sys.executable, ...]), achieving code execution with the privileges of the victim's local user process. Version 3.17.1 fixes the issue.

The Cortex MCP server (neuro-cortex-memory), a cross-platform persistent memory MCP, prior to version 3.17.1 treats the CLAUDE_PROJECT_DIR environment variable — automatically set by Claude Code to the currently open project directory — as a trusted Cortex developer checkout. When the open_visualization tool is invoked, _find_dev_source() resolves the user's active project directory as a candidate Cortex source root. The only validation performed by _is_cortex_root() is a check for the presence of an mcp_server/ subdirectory and a ui/unified-viz.html file. An attacker who places these two marker files in a malicious repository can cause Cortex to execute an arbitrary mcp_server/server/visualize_bootstrap.py from that directory via subprocess.run([sys.executable, ...]), achieving code execution with the privileges of the victim's local user process. Version 3.17.1 fixes the issue.

Untrusted Project Bootstrap Code Execution via CLAUDE_PROJECT_DIR

Summary

The Cortex MCP server (neuro-cortex-memory) treats the CLAUDE_PROJECT_DIR environment variable — automatically set by Claude Code to the currently open project directory — as a trusted Cortex developer checkout. When the open_visualization tool is invoked, _find_dev_source() resolves the user's active project directory as a candidate Cortex source root. The only validation performed by _is_cortex_root() is a check for the presence of an mcp_server/ subdirectory and a ui/unified-viz.html file. An attacker who places these two marker files in a malicious repository can cause Cortex to execute an arbitrary mcp_server/server/visualize_bootstrap.py from that directory via subprocess.run([sys.executable, ...]), achieving code execution with the privileges of the victim's local user process. CVSS v3.1 Base Score: 7.8 (High).

Details

The vulnerability originates in _find_dev_source() inside mcp_server/handlers/open_visualization.py. The function builds a list of candidate directories by iterating over the environment variables CORTEX_DEV_ROOT and CLAUDE_PROJECT_DIR:

# mcp_server/handlers/open_visualization.py:73-76
for env in ("CORTEX_DEV_ROOT", "CLAUDE_PROJECT_DIR"):
    v = os.environ.get(env)
    if v:
        candidates.append(Path(v))

CLAUDE_PROJECT_DIR is set automatically by the Claude Code IDE extension to whichever directory the user has currently open. This means any project the user opens is silently treated as a candidate Cortex source root.

Each candidate is then validated by _is_cortex_root() (lines 65–70), which only verifies that the directory contains an mcp_server/ subdirectory and a ui/unified-viz.html file — trivial markers that an attacker can replicate:

# mcp_server/handlers/open_visualization.py:65-70
def _is_cortex_root(path: Path) -> bool:
    return (path / "mcp_server").is_dir() and \
           (path / "ui" / "unified-viz.html").is_file()

There is no git remote identity check, no cryptographic signature verification, no release path allowlist, and no explicit developer opt-in requirement. Once a directory passes _is_cortex_root(), the handler constructs a bootstrap path and executes it unconditionally:

# mcp_server/handlers/open_visualization.py:179-185
bootstrap_path = dev_src / "mcp_server" / "server" / "visualize_bootstrap.py"
if bootstrap_path.is_file():
    ...
    proc = subprocess.run(
        [sys.executable, str(bootstrap_path)],
    )

A secondary code-execution path exists in mcp_server/server/http_launcher.py:80-83 and 273-275, where the same CLAUDE_PROJECT_DIR-derived dev source is used to rsync attacker-controlled files into the Cortex plugin cache directory before serving them.

Entry point: MCP tool open_visualization, registered at mcp_server/tool_registry_core.py:194-207 (no authentication required at tool layer). The tool is reachable through the standard stdio MCP transport started in mcp_server/__main__.py:66.

PoC

Prerequisites

• Cortex (neuro-cortex-memory ≥ 3.17.0) installed and importable.
• Victim opens an attacker-controlled project directory in Claude Code (sets CLAUDE_PROJECT_DIR automatically) or the attacker otherwise controls CLAUDE_PROJECT_DIR.
• Victim invokes /cortex-visualize or triggers the open_visualization MCP tool (e.g., by selecting a visualization command in the Claude Code interface).

Inline PoC

import asyncio, os, tempfile
from pathlib import Path
from mcp_server.handlers import open_visualization as ov

base = Path(tempfile.mkdtemp(prefix="cortex-malicious-project-"))
(base / "mcp_server" / "server").mkdir(parents=True)
(base / "ui").mkdir()
(base / "ui" / "unified-viz.html").write_text("<html>attacker</html>", encoding="utf-8")

sentinel = Path("/tmp/cortex-open-visualization-poc-owned")
if sentinel.exists():
   …

The Cortex MCP server (neuro-cortex-memory), a cross-platform persistent memory MCP, prior to version 3.17.1 treats the CLAUDE_PROJECT_DIR environment variable — automatically set by Claude Code to the currently open project directory — as a trusted Cortex developer checkout. When the open_visualization tool is invoked, _find_dev_source() resolves the user's active project directory as a candidate Cortex source root. The only validation performed by _is_cortex_root() is a check for the presence of an mcp_server/ subdirectory and a ui/unified-viz.html file. An attacker who places these two marker files in a malicious repository can cause Cortex to execute an arbitrary mcp_server/server/visualize_bootstrap.py from that directory via subprocess.run([sys.executable, ...]), achieving code execution with the privileges of the victim's local user process. Version 3.17.1 fixes the issue.

The Cortex MCP server (neuro-cortex-memory), a cross-platform persistent memory MCP, prior to version 3.17.1 treats the CLAUDE_PROJECT_DIR environment variable — automatically set by Claude Code to the currently open project directory — as a trusted Cortex developer checkout. When the open_visualization tool is invoked, _find_dev_source() resolves the user's active project directory as a candidate Cortex source root. The only validation performed by _is_cortex_root() is a check for the presence of an mcp_server/ subdirectory and a ui/unified-viz.html file. An attacker who places these two marker files in a malicious repository can cause Cortex to execute an arbitrary mcp_server/server/visualize_bootstrap.py from that directory via subprocess.run([sys.executable, ...]), achieving code execution with the privileges of the victim's local user process. Version 3.17.1 fixes the issue.

Untrusted Project Bootstrap Code Execution via CLAUDE_PROJECT_DIR

Summary

The Cortex MCP server (neuro-cortex-memory) treats the CLAUDE_PROJECT_DIR environment variable — automatically set by Claude Code to the currently open project directory — as a trusted Cortex developer checkout. When the open_visualization tool is invoked, _find_dev_source() resolves the user's active project directory as a candidate Cortex source root. The only validation performed by _is_cortex_root() is a check for the presence of an mcp_server/ subdirectory and a ui/unified-viz.html file. An attacker who places these two marker files in a malicious repository can cause Cortex to execute an arbitrary mcp_server/server/visualize_bootstrap.py from that directory via subprocess.run([sys.executable, ...]), achieving code execution with the privileges of the victim's local user process. CVSS v3.1 Base Score: 7.8 (High).

Details

The vulnerability originates in _find_dev_source() inside mcp_server/handlers/open_visualization.py. The function builds a list of candidate directories by iterating over the environment variables CORTEX_DEV_ROOT and CLAUDE_PROJECT_DIR:

# mcp_server/handlers/open_visualization.py:73-76
for env in ("CORTEX_DEV_ROOT", "CLAUDE_PROJECT_DIR"):
    v = os.environ.get(env)
    if v:
        candidates.append(Path(v))

CLAUDE_PROJECT_DIR is set automatically by the Claude Code IDE extension to whichever directory the user has currently open. This means any project the user opens is silently treated as a candidate Cortex source root.

Each candidate is then validated by _is_cortex_root() (lines 65–70), which only verifies that the directory contains an mcp_server/ subdirectory and a ui/unified-viz.html file — trivial markers that an attacker can replicate:

# mcp_server/handlers/open_visualization.py:65-70
def _is_cortex_root(path: Path) -> bool:
    return (path / "mcp_server").is_dir() and \
           (path / "ui" / "unified-viz.html").is_file()

There is no git remote identity check, no cryptographic signature verification, no release path allowlist, and no explicit developer opt-in requirement. Once a directory passes _is_cortex_root(), the handler constructs a bootstrap path and executes it unconditionally:

# mcp_server/handlers/open_visualization.py:179-185
bootstrap_path = dev_src / "mcp_server" / "server" / "visualize_bootstrap.py"
if bootstrap_path.is_file():
    ...
    proc = subprocess.run(
        [sys.executable, str(bootstrap_path)],
    )

A secondary code-execution path exists in mcp_server/server/http_launcher.py:80-83 and 273-275, where the same CLAUDE_PROJECT_DIR-derived dev source is used to rsync attacker-controlled files into the Cortex plugin cache directory before serving them.

Entry point: MCP tool open_visualization, registered at mcp_server/tool_registry_core.py:194-207 (no authentication required at tool layer). The tool is reachable through the standard stdio MCP transport started in mcp_server/__main__.py:66.

PoC

Prerequisites

• Cortex (neuro-cortex-memory ≥ 3.17.0) installed and importable.
• Victim opens an attacker-controlled project directory in Claude Code (sets CLAUDE_PROJECT_DIR automatically) or the attacker otherwise controls CLAUDE_PROJECT_DIR.
• Victim invokes /cortex-visualize or triggers the open_visualization MCP tool (e.g., by selecting a visualization command in the Claude Code interface).

Inline PoC

import asyncio, os, tempfile
from pathlib import Path
from mcp_server.handlers import open_visualization as ov

base = Path(tempfile.mkdtemp(prefix="cortex-malicious-project-"))
(base / "mcp_server" / "server").mkdir(parents=True)
(base / "ui").mkdir()
(base / "ui" / "unified-viz.html").write_text("<html>attacker</html>", encoding="utf-8")

sentinel = Path("/tmp/cortex-open-visualization-poc-owned")
if sentinel.exists():
   …

Untrusted Project Bootstrap Code Execution via CLAUDE_PROJECT_DIR

Summary

The Cortex MCP server (neuro-cortex-memory) treats the CLAUDE_PROJECT_DIR environment variable — automatically set by Claude Code to the currently open project directory — as a trusted Cortex developer checkout. When the open_visualization tool is invoked, _find_dev_source() resolves the user's active project directory as a candidate Cortex source root. The only validation performed by _is_cortex_root() is a check for the presence of an mcp_server/ subdirectory and a ui/unified-viz.html file. An attacker who places these two marker files in a malicious repository can cause Cortex to execute an arbitrary mcp_server/server/visualize_bootstrap.py from that directory via subprocess.run([sys.executable, ...]), achieving code execution with the privileges of the victim's local user process. CVSS v3.1 Base Score: 7.8 (High).

Details

The vulnerability originates in _find_dev_source() inside mcp_server/handlers/open_visualization.py. The function builds a list of candidate directories by iterating over the environment variables CORTEX_DEV_ROOT and CLAUDE_PROJECT_DIR:

# mcp_server/handlers/open_visualization.py:73-76
for env in ("CORTEX_DEV_ROOT", "CLAUDE_PROJECT_DIR"):
    v = os.environ.get(env)
    if v:
        candidates.append(Path(v))

CLAUDE_PROJECT_DIR is set automatically by the Claude Code IDE extension to whichever directory the user has currently open. This means any project the user opens is silently treated as a candidate Cortex source root.

Each candidate is then validated by _is_cortex_root() (lines 65–70), which only verifies that the directory contains an mcp_server/ subdirectory and a ui/unified-viz.html file — trivial markers that an attacker can replicate:

# mcp_server/handlers/open_visualization.py:65-70
def _is_cortex_root(path: Path) -> bool:
    return (path / "mcp_server").is_dir() and \
           (path / "ui" / "unified-viz.html").is_file()

There is no git remote identity check, no cryptographic signature verification, no release path allowlist, and no explicit developer opt-in requirement. Once a directory passes _is_cortex_root(), the handler constructs a bootstrap path and executes it unconditionally:

# mcp_server/handlers/open_visualization.py:179-185
bootstrap_path = dev_src / "mcp_server" / "server" / "visualize_bootstrap.py"
if bootstrap_path.is_file():
    ...
    proc = subprocess.run(
        [sys.executable, str(bootstrap_path)],
    )

A secondary code-execution path exists in mcp_server/server/http_launcher.py:80-83 and 273-275, where the same CLAUDE_PROJECT_DIR-derived dev source is used to rsync attacker-controlled files into the Cortex plugin cache directory before serving them.

Entry point: MCP tool open_visualization, registered at mcp_server/tool_registry_core.py:194-207 (no authentication required at tool layer). The tool is reachable through the standard stdio MCP transport started in mcp_server/__main__.py:66.

PoC

Prerequisites

• Cortex (neuro-cortex-memory ≥ 3.17.0) installed and importable.
• Victim opens an attacker-controlled project directory in Claude Code (sets CLAUDE_PROJECT_DIR automatically) or the attacker otherwise controls CLAUDE_PROJECT_DIR.
• Victim invokes /cortex-visualize or triggers the open_visualization MCP tool (e.g., by selecting a visualization command in the Claude Code interface).

Inline PoC

import asyncio, os, tempfile
from pathlib import Path
from mcp_server.handlers import open_visualization as ov

base = Path(tempfile.mkdtemp(prefix="cortex-malicious-project-"))
(base / "mcp_server" / "server").mkdir(parents=True)
(base / "ui").mkdir()
(base / "ui" / "unified-viz.html").write_text("<html>attacker</html>", encoding="utf-8")

sentinel = Path("/tmp/cortex-open-visualization-poc-owned")
if sentinel.exists():
   …