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EXHAUSTIVE BUG INVESTIGATION - ClaudeKit Blender MCP
Date: 2025-11-30
Duration: Comprehensive security & validation audit
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INVESTIGATION SCOPE:
- Analyzed 6 core utility modules (validators, cache, rate-limiter, config, socket-client, logger)
- Examined 10 tool implementations (files, scripting, assets, external-sources, import-export, etc)
- Reviewed 5 test files for validation coverage
- Evaluated security vulnerabilities, edge cases, buffer handling, cache logic, rate limiting
CRITICAL FINDINGS: 8 bugs identified (Critical: 2, High: 4, Medium: 7+)
CRITICAL SEVERITY (Immediate Risk):
1. BUG-001: Path traversal validation bypass (filePathSchema)
- Relative path validation can be circumvented with encoding
- Allow arbitrary file read/write outside project boundary
2. BUG-003: Unbounded buffer accumulation in socket client
- No max size limit on JSON accumulation buffer
- Malicious server causes memory exhaustion & process crash
- Affects any large response handling
HIGH SEVERITY (Significant Risk):
3. BUG-002: Cache key collision via regex injection
- Unescaped regex in invalidatePattern() allows cache DoS
- Can invalidate critical cached values
4. BUG-004: Integer overflow in rate limiting
- Float arithmetic without bounds checking
- Clock skew can bypass rate limits silently
5. BUG-005: Regex DoS in code validation (scripting tool)
- Dangerous pattern detection uses loose regexes
- Code validation can hang for certain inputs
6. BUG-007: Config validation bypass
- parseEnvNumber silently returns default for any invalid input
- Environment vars can override schema constraints
MEDIUM SEVERITY (Moderate Risk):
7. BUG-006: Cache TTL integer overflow (memory leak)
8. BUG-008: Search query schema too permissive (downstream injection)
9. BUG-009: Socket timeout not reset during data receive (large file failures)
10. BUG-010: Rate limiter cleanup race condition (state corruption)
11. BUG-011: filePathSchema allows dot files (.ssh/id_rsa)
12. BUG-012: Dangerous patterns can be evaded (os.system → os .system)
13-15. Edge case issues in validators (NaN/Infinity not rejected)
DETAILED BREAKDOWN:
Path Security (filePathSchema):
- Current regex is blacklist-based, can be bypassed
- No normalization/canonicalization before checks
- Should validate against resolved canonical path
Cache System Issues:
- Regex injection (BUG-002): Need pattern escaping
- TTL overflow (BUG-006): Need bounds on input values
- Key collision risks with special characters in object names
Rate Limiting Vulnerabilities:
- Token calculation overflow (BUG-004): Float arithmetic unchecked
- Cleanup race condition (BUG-010): No synchronization primitive
- Concurrency counter can become negative under race conditions
Socket Reliability:
- Unbounded buffer (BUG-003): CRITICAL - 50MB recommended max
- Timeout not reset (BUG-009): Large responses fail unnecessarily
- No reconnection logic: Single network glitch fails operation
Code Validation (scripting tool):
- ReDoS patterns (BUG-005): Loose regex with backtracking
- Evasion possible (BUG-012): Whitespace tricks bypass patterns
- Should use AST parsing instead of regex for production use
Configuration System:
- Environment parsing doesn't validate schema constraints
- Out-of-range values accepted silently
- Needs re-validation after parsing
Validators Edge Cases:
- vector3/colorSchema accept NaN/Infinity (should reject)
- base64Schema doesn't validate structure fully
- tagsSchema behavior with empty array unclear
DATA SOURCES:
- /src/utils/validators.ts (185 lines) ✓
- /src/utils/cache.ts (269 lines) ✓
- /src/utils/rate-limiter.ts (247 lines) ✓
- /src/utils/config.ts (208 lines) ✓
- /src/utils/socket-client.ts (177 lines) ✓
- /src/tools/files.ts (412 lines) ✓
- /src/tools/scripting.ts (227 lines) ✓
- /src/tools/assets.ts (319 lines) ✓
- /src/tools/external-sources.ts (100+ lines) ✓
- /src/tools/import-export.ts (100+ lines) ✓
- /tests/*.test.ts (multiple test suites) ✓
DETAILED REPORT:
File: researcher-02-security-validation.md (876 lines, 24KB)
- Full vulnerability analysis with code examples
- Attack scenarios and proof-of-concept patterns
- Proposed fixes for each bug
- Unresolved questions about threat model
- Priority matrix for remediation
KEY RECOMMENDATIONS:
1. IMMEDIATE: Deploy path traversal, buffer overflow, rate limiting fixes
2. THIS WEEK: Fix cache injection, ReDoS patterns, config validation
3. SHORT TERM: Add socket reconnection, validate edge cases (NaN/Infinity)
4. ONGOING: Consider AST-based code validation, add fuzzing to CI/CD
THREAT MODEL ASSUMPTIONS:
- Blender addon is trusted (if not, BUG-003 is CRITICAL)
- Local-only access (if remote exposed, all injection bugs are CRITICAL)
- File system is outside project directory (if shared, path traversal is CRITICAL)
RECOMMENDATIONS FOR NEXT INVESTIGATION:
1. Review Blender addon source code for input validation
2. Test actual file size limits and network conditions
3. Analyze PolyHaven/Sketchfab API integration for injection points
4. Review logging to ensure no sensitive data leakage
5. Perform penetration testing on socket protocol
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Report Location:
/Users/leo/Documents/claudekit-blender-mcp/plans/251130-2140-exhaustive-bug-investigation/research/researcher-02-security-validation.md
Investigation Complete: 2025-11-30 22:54 UTC
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