Bugs/improvements/security issues

[cktang88]

From codex:

Critical — Security Vulnerabilities

1. Shell injection via OAuth URL

• File: src/auth/oauth.ts:53
• Passes unsanitized URL to exec(). A crafted URL can execute arbitrary shell commands.
• Fix: Use execFile() or child_process.spawn() instead.

2. Plaintext credential storage

• File: src/auth/credentials.ts
• API keys and OAuth tokens are stored as unencrypted JSON in ~/.mmx/.
• One cat command = full account takeover.
• Fix: Use OS keychain integration (keytar, security on macOS).

3. Insecure file permissions are warnings, not errors

• File: src/auth/credentials.ts:39-50
• Detects 0o644 on credential files, logs a warning, and continues.
• On shared systems, tokens are readable by other users.
• Fix: Refuse to load credentials with insecure permissions.

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High — Silent Failures & Data Corruption

4. Streaming errors silently swallowed

• File: src/commands/text/chat.ts:194
• SSE parse errors are caught and dropped. Output is silently corrupted mid-stream with no indication to the user.

5. Concurrent token refresh corrupts credentials

• File: src/auth/credentials.ts, src/auth/refresh.ts
• Two parallel mmx invocations both read the same refresh token, both call the token endpoint, one invalidates the other's.
• Fix: File locking on credential read/write.

6. Network truncation goes undetected

• File: src/files/download.ts:17
• Defaults contentLength to 0 when header is missing. Never compares received bytes vs expected. User gets a truncated file and thinks it succeeded.

7. Polling discards API failure context

• File: src/polling/poll.ts:35-40
• Throws 'Task failed.' with zero detail from the API response. Users cannot diagnose why video/music generation failed.

8. Corrupted credentials return null silently

• File: src/auth/credentials.ts:15-21
• JSON parse errors on the credentials file return null with a stderr warning. Non-interactive callers get silent auth failure.

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High — Crash Bugs (Unhandled Exceptions)

9. Non-null assertion on API audio data

• File: src/output/audio.ts:23
• response.data.audio! — null/undefined audio = runtime crash. Odd-length hex string = Buffer.from throws.

10. Base64 memory bomb

• File: src/commands/vision/describe.ts:29-35
• Reads entire image into memory via arrayBuffer() with no size limit. 500MB image = OOM kill.

11. Tool JSON parsing has no error handling

• File: src/commands/text/chat.ts:136-145
• Tries JSON.parse, falls back to readFileSync. Missing file or invalid JSON = uncaught exception.

12. Disk full during file write

• Files: src/output/audio.ts, src/files/download.ts
• Neither writeFileSync nor createWriteStream handles ENOSPC. Partial corrupt files left behind.

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Medium — Correctness Bugs

13. File ID heuristic is wrong

• File: src/commands/vision/describe.ts:76-77
• Uses "no dot and not http" to detect file IDs. UUIDs, filenames with dashes, dotless filenames all misclassified.

14. Voice language filter is too greedy

• File: src/commands/speech/voices.ts:18
• Case-insensitive substring match means --language ch matches Chinese, Czech, and Icelandic. No "no results found" feedback.

15. Region detection falls back silently

• File: src/config/detect-region.ts:10-21
• Probes quota endpoint. If a CN-only key fails the global probe, defaults to 'global' — user gets cryptic errors on every subsequent command.

16. File overwrite without warning

• File: src/commands/image/generate.ts:152-163
• Silently overwrites existing files. Batch failures leave partial state with no rollback.

17. --output json ignored in quiet mode

• File: src/commands/image/generate.ts:165-167
• Dumps raw file paths even when user requested JSON output.

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Medium — Missing Validation

18. No flag value validation anywhere

• Flag parsing accepts anything: --timeout abc becomes NaN, --region invalid passes through, --max-tokens 999999999 is unchecked. Crashes happen downstream, not at the boundary.

19. No request timeout on token refresh

• File: src/auth/refresh.ts
• HTTP call with no timeout. Unresponsive server = CLI hangs forever.

20. No request timeout on polling

• File: src/polling/poll.ts
• requestJson() calls during task status checks have no per-request timeout.

21. No size validation before base64 encoding

• File: src/commands/image/generate.ts:122-125
• Reads reference image with readFileSync and base64-encodes without file size check.

22. SSE stream never validates content-type

• File: src/client/stream.ts
• Assumes response body is text SSE. HTML error pages are parsed as SSE, producing garbage output.