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fix(tui): prevent path traversal in MCP storage via server name sanitization #83

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fix(tui): prevent path traversal in MCP storage via server name sanitization #83

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fix(tui): prevent path traversal in MCP storage via server name sanit…
echobt Feb 4, 2026
e7a17ae
fix: apply rustfmt formatting
echobt Feb 4, 2026
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76 changes: 75 additions & 1 deletion src/cortex-tui/src/mcp_storage.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,37 @@ use anyhow::{Context, Result};
use cortex_common::AppDirs;
use serde::{Deserialize, Serialize};

// ============================================================
// SECURITY HELPERS
// ============================================================

/// Sanitize a server name to prevent path traversal attacks.
///
/// Only allows alphanumeric characters, hyphens, and underscores.
/// Any other characters (including path separators) are replaced with underscores.
fn sanitize_server_name(name: &str) -> String {
name.chars()
.map(|c| {
if c.is_ascii_alphanumeric() || c == '-' || c == '_' {
c
} else {
'_'
}
})
.collect()
}

/// Validate a server name for safe filesystem use.
///
/// Returns true if the name contains only safe characters.
#[allow(dead_code)]
pub fn validate_server_name(name: &str) -> bool {
!name.is_empty()
&& name
.chars()
.all(|c| c.is_ascii_alphanumeric() || c == '-' || c == '_')
}
Comment on lines +41 to +47
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@greptile-apps greptile-apps bot Feb 4, 2026

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validate_server_name is unused but should be called before saving to prevent name collision issues

The current implementation allows saving servers with invalid names (e.g., "../etc"), which get sanitized to "________etc" for the filename. This creates a collision risk where "../etc" and "________etc" would map to the same file. Consider validating names in save_server():

pub fn save_server(&self, server: &StoredMcpServer) -> Result<()> {
    if !validate_server_name(&server.name) {
        anyhow::bail!("Invalid server name: {}", server.name);
    }
    // ... rest of implementation
}
Prompt To Fix With AI 
This is a comment left during a code review.
Path: src/cortex-tui/src/mcp_storage.rs
Line: 41:47

Comment:
`validate_server_name` is unused but should be called before saving to prevent name collision issues

The current implementation allows saving servers with invalid names (e.g., `"../etc"`), which get sanitized to `"________etc"` for the filename. This creates a collision risk where `"../etc"` and `"________etc"` would map to the same file. Consider validating names in `save_server()`:

```
pub fn save_server(&self, server: &StoredMcpServer) -> Result<()> {
    if !validate_server_name(&server.name) {
        anyhow::bail!("Invalid server name: {}", server.name);
    }
    // ... rest of implementation
}
```

How can I resolve this? If you propose a fix, please make it concise.


/// MCP transport type
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
#[serde(rename_all = "lowercase")]
Expand Down Expand Up @@ -158,8 +189,11 @@ impl McpStorage {
}

/// Get the path to a server's config file
///
/// The server name is sanitized to prevent path traversal attacks.
fn server_path(&self, name: &str) -> PathBuf {
self.mcps_dir.join(format!("{}.json", name))
let sanitized_name = sanitize_server_name(name);
self.mcps_dir.join(format!("{}.json", sanitized_name))
}

/// Save an MCP server configuration
Expand Down Expand Up @@ -372,4 +406,44 @@ mod tests {
let result = storage.load_server("nonexistent").unwrap();
assert!(result.is_none());
}

#[test]
fn test_sanitize_server_name() {
// Normal names stay the same
assert_eq!(sanitize_server_name("my-server"), "my-server");
assert_eq!(sanitize_server_name("server_123"), "server_123");

// Path traversal attempts get sanitized
assert_eq!(sanitize_server_name("../../../etc"), "________etc");
assert_eq!(sanitize_server_name("test/subdir"), "test_subdir");
assert_eq!(sanitize_server_name("test\\windows"), "test_windows");
}

#[test]
fn test_validate_server_name() {
// Valid names
assert!(validate_server_name("my-server"));
assert!(validate_server_name("server_123"));
assert!(validate_server_name("ABC"));

// Invalid names
assert!(!validate_server_name("../../../etc"));
assert!(!validate_server_name("test/subdir"));
assert!(!validate_server_name(""));
assert!(!validate_server_name("name with spaces"));
}

#[test]
fn test_server_path_traversal() {
let (storage, tmp) = test_storage();
let base_dir = tmp.path().to_path_buf();

// Attempt path traversal
let malicious_name = "../../../etc/passwd";
let result_path = storage.server_path(malicious_name);

// The result should still be under mcps_dir
assert!(result_path.starts_with(base_dir.join("mcps")));
assert!(!result_path.to_string_lossy().contains(".."));
}
}
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