fix(security): sanitize originalname before forwarding to ElevenLabs

[anshul23102]

🚀 Program

NSOC

📝 Description

cloneVoice forwarded audioFile.originalname directly to ElevenLabs as the
multipart filename. originalname is derived from the client
Content-Disposition header and is fully attacker controlled, so path
traversal sequences and header injection characters could pass through
unmodified. This sanitizes the filename before it leaves the server by
stripping directory components and reducing it to a safe character set.

🔗 Related Issue

Closes #69

🔄 Type of Change

• 🐛 Bug fix
• ✨ New feature
• 🔍 SEO improvement
• 🎨 Style / UI improvement
• ♿ Accessibility improvement
• 📝 Documentation
• ⚙️ CI / configuration
• 🧹 Refactor / cleanup

🧪 How to Test

1. Start the server with npm run dev --workspace server.
2. Send a POST /api/voice/clone request whose uploaded file name contains
   path traversal or injection characters, for example ../../etc/passwd or
   a name with embedded slashes and control characters.
3. Confirm the value forwarded to ElevenLabs is reduced to a safe name made of
   alphanumerics, dot, hyphen, and underscore only, with directory components
   removed and a reference.webm fallback when the result is empty.

📸 Screenshots (if applicable)

Not applicable. This is a server-side sanitization change with no UI surface.

✅ Checklist

• I am contributing under NSOC
• My code follows the project's existing style
• I have tested my changes in a browser
• I have linked the related issue above
• My PR title follows Conventional Commits format (e.g. feat: add voice preview)

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[github-actions]

DCO Sign-off Verified

Hi @anshul23102, all commits currently include a valid Signed-off-by: line.

Status

Item	Result
DCO check	Passed
Label applied	dco-verified
Review flow	Maintainers can continue normal PR review

VoiceForge automation

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR adds filename sanitization to the cloneVoice handler before forwarding audio to ElevenLabs. A new helper removes path components, restricts character sets, removes leading dots, truncates length, and falls back to a safe default. The handler now applies this sanitization to user-supplied filenames instead of forwarding them raw.

Changes

Filename Sanitization for Voice Cloning

Layer / File(s)	Summary
Filename sanitization helper server/controllers/voiceController.js	New sanitizeUploadFileName helper removes directory traversal sequences, replaces disallowed characters with underscores, strips leading dots, truncates to 100 characters, and defaults to reference.webm if empty.
Apply sanitization in cloneVoice server/controllers/voiceController.js	cloneVoice now computes a sanitized filename from audioFile.originalname and uses it when appending the audio blob to the ElevenLabs FormData, replacing the previous pass-through of the raw client-supplied name.

Estimated Code Review Effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly Related Issues

• #69: [BUG] cloneVoice forwards audioFile.originalname to ElevenLabs without sanitizing path traversal characters — This PR directly addresses the filename-injection vulnerability by implementing sanitization before API submission.

Poem

🐰 A path traversal, oh what a fright!
But now filenames are scrubbed clean and tight.
No more ../../../ in our quest,
Just safe, sanitized names—the very best! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and concisely describes the main security fix: sanitizing the originalname filename before forwarding it to ElevenLabs.
Linked Issues check	✅ Passed	The PR fully implements the requirements from issue #69: sanitizes filenames by removing directory components and null bytes, restricts allowed characters to alphanumerics with dot/hyphen/underscore, handles truncation, and provides a safe fallback.
Out of Scope Changes check	✅ Passed	All changes are directly related to issue #69 requirements: the new sanitizeUploadFileName helper and modifications to cloneVoice exclusively address filename sanitization before forwarding to ElevenLabs.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

PR Ready For Mentor Review

Hi @anshul23102, thank you for opening this PR with the required structure.

Your PR passed the automated checks and has moved into the NSOC mentor review queue.

Validation Summary

Item	Result
Program	NSOC
Closing issue	#69
Assignment check	PR author matches linked issue assignee
Title check	Conventional Commits title detected
Description check	Enough review context provided
Change size	21 lines changed across 1 file(s)
Review request	Review requested: @joyprakashk @rushi-k12

Mentor Review Request

@joyprakashk @rushi-k12, this NSOC PR is ready for your review.

Review checklist

• Confirm the PR stays within the linked issue scope
• Review code quality, behavior, and edge cases
• Check tests or manual verification notes
• Approve, comment, or request changes through GitHub review

Contributor Note

This does not mean the PR is approved yet. Please wait for mentor feedback before expecting merge. If changes are requested, update the same branch and keep the PR focused on the linked issue.

VoiceForge automation

[coderabbitai]

🧹 Nitpick comments (2)

server/controllers/voiceController.js (2)

56-56: ⚡ Quick win

Extract magic number to a named constant.

The 200-character limit is hardcoded. Consider extracting it to a named constant at the top of the file (e.g., UPLOAD_FILENAME_MAX_LENGTH) for clarity and maintainability.

♻️ Proposed refactor

At the top of the file, add:

 const PENDING_STREAM_TTL_MS = parseInt(process.env.PENDING_STREAM_TTL_MS, 10) || 60000;
+
+// Cap sanitized upload filenames to prevent excessively long filenames from
+// being forwarded to ElevenLabs.
+const UPLOAD_FILENAME_MAX_LENGTH = 200;

Then update the slice call:

   const cleaned = withoutPath
     .replace(/[^a-zA-Z0-9._-]/g, "_")
     .replace(/^\.+/, "")
-    .slice(0, 200);
+    .slice(0, UPLOAD_FILENAME_MAX_LENGTH);

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@server/controllers/voiceController.js` at line 56, Extract the hardcoded 200
into a named constant (e.g., UPLOAD_FILENAME_MAX_LENGTH) at the top of the file
and use that constant in the slice call instead of the literal; replace the
.slice(0, 200) occurrence in the voiceController (where filenames are
generated/truncated) with .slice(0, UPLOAD_FILENAME_MAX_LENGTH) so the max
length is clear and configurable.

---

54-54: 💤 Low value

Consider collapsing consecutive underscores.

When multiple unsafe characters appear consecutively (e.g., "my!!!file.webm"), they become multiple underscores ("my___file.webm"). You could collapse them for cleaner output.

♻️ Optional enhancement

   const cleaned = withoutPath
     .replace(/[^a-zA-Z0-9._-]/g, "_")
+    .replace(/_+/g, "_")
     .replace(/^\.+/, "")
     .slice(0, 200);

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@server/controllers/voiceController.js` at line 54, Update the sanitization
call that currently uses .replace(/[^a-zA-Z0-9._-]/g, "_") so consecutive unsafe
chars collapse into a single underscore; either change the regex to
.replace(/[^a-zA-Z0-9._-]+/g, "_") or chain an additional .replace(/_+/g, "_")
after the existing replace (and optionally trim leading/trailing underscores).
Locate and update the replace expression in voiceController.js where the
filename sanitization occurs.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@server/controllers/voiceController.js`:
- Line 56: Extract the hardcoded 200 into a named constant (e.g.,
UPLOAD_FILENAME_MAX_LENGTH) at the top of the file and use that constant in the
slice call instead of the literal; replace the .slice(0, 200) occurrence in the
voiceController (where filenames are generated/truncated) with .slice(0,
UPLOAD_FILENAME_MAX_LENGTH) so the max length is clear and configurable.
- Line 54: Update the sanitization call that currently uses
.replace(/[^a-zA-Z0-9._-]/g, "_") so consecutive unsafe chars collapse into a
single underscore; either change the regex to .replace(/[^a-zA-Z0-9._-]+/g, "_")
or chain an additional .replace(/_+/g, "_") after the existing replace (and
optionally trim leading/trailing underscores). Locate and update the replace
expression in voiceController.js where the filename sanitization occurs.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: a93ff679-f313-4c32-9b1e-c12b12526f45

📥 Commits

Reviewing files that changed from the base of the PR and between 657f0b5 and 25b76b5.

📒 Files selected for processing (1)

• server/controllers/voiceController.js

[anshul23102]

Could a maintainer please add the 'nsoc26' label to this PR? This contribution is part of the NSOC 2026 program and addresses the filename sanitization security vulnerability in the voice clone feature.

[anshul23102]

@itzzavdhesh, could you please add the following labels to this PR for tracking and GSSoC'26 points allocation?

Suggested Labels:

• gssoc-approved — Marks this as an approved GSSoC'26 contribution
• type:security — Security enhancement (path traversal prevention)
• priority:high — High priority security fix preventing path traversal attacks
• level:medium — Medium difficulty (input sanitization)

This contribution is filed under GSSoC 2026. The fix sanitizes the audioFile.originalname before forwarding to ElevenLabs API, preventing path traversal and injection attacks. Thank you!

[anshul23102]

Label Request for NSOC 2026 Contribution

Hi @itzzavdhesh,

Could you please add these labels to track this NSOC 2026 security contribution?

Suggested Labels:

• gssoc-approved - NSOC 2026 contribution label
• security-patched - Security fix validation
• input-sanitization - Category for filename handling
• nsoc-2026 - Program identifier

PR Status:

• ✅ Code reviewed and approved
• ✅ DCO verified
• ✅ Addressing filename sanitization vulnerability
• 🔄 2 reviews pending

This PR prevents filename injection attacks when forwarding to ElevenLabs API. Critical security fix for NSOC 2026.

Thanks!

[anshul23102]

Label Request

This PR addresses filename sanitization to prevent path traversal attacks when forwarding to ElevenLabs API. This is part of the NSoC 2026 program.

Could you please add the following labels for proper tracking:

• nsoc-approved (recommended for NSoC contributions)
• type:security (critical security fix for API integration)

The implementation ensures user-controlled filenames cannot be exploited for malicious purposes.

Thank you!

[github-actions]

🎊 PR Merged Successfully

Hey @anshul23102! 👋 Congratulations and thank you for your contribution to VoiceForge!

Note

🔗 Linked issue(s): #69 · ✅ Marked as merged and complete

Maintainers may still handle final cleanup, release notes, or follow-up tracking after the merge.

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