Bug: Protocol Fees Charged on Unexecuted Limit Orders #124
Description
Summary
Post Only limit orders that are placed and canceled without any execution are incurring fees of 0.075%-0.137%. According to DeepBook V3 documentation, fees should only apply to executed trades.
Environment
- Platform: deeptrade.io
- Wallet:
0xa46617da774561178446eb08a91c422427a9b079c56304e6fbc8328a21862d89 - Dates: October 30-31, 2025
- DEEP Staking: None
- Order Type: Post Only limit maker orders
Complete Transaction History
| Transaction Hash | Date (UTC) | USDC Change | Order ID | Market | Action |
|---|---|---|---|---|---|
2kMfBFaZiCKYsQeLGcab1bUJWUtKsHgh3jHoiRRDDn7f |
Oct 31, 2025 20:19:00 | +10,014.502500 | 922521671144661420389868722210 | xBTC-USDC | CANCEL |
AxNBpirqGkAbgeYRPkqk2pmvKsAEw9XVsvocJsBZ2i4A |
Oct 31, 2025 20:18:27 | -10,022.004000 | - | xBTC-USDC | PLACE |
9CD8Up2GEdp29dDCyBovkFa2t2fBy4QFVRqaDDVvfytK |
Oct 31, 2025 20:17:52 | +9,993.695024 | 276885646993124443453501187 | NS-USDC | CANCEL |
u2ypxcAsSvhX4ZbqYnHmaeSWhEHVJeRk4g5gRkisjnf |
Oct 31, 2025 20:17:12 | +2,489.393798 | 224312407954754891724268725825 | xBTC-USDC | CANCEL |
GyJG5F9wkvinrU91HNeDMCpUz22V4Vd9445gBDS27bCb |
Oct 31, 2025 14:02:10 | -10,007.427740 | - | NS-USDC | PLACE |
4V6ryGtLbeHvyV13AMHC9dV9PAtYTME28nUU7EQ4N62J |
Oct 31, 2025 14:00:52 | +10,007.800724 | 276885646993124443453506384 | NS-USDC | CANCEL |
GdewvPDDHPMQAUrwhUA3JpM19of1y1d1QWcRZoZWFUTv |
Oct 31, 2025 14:00:15 | -2,486.563265 | - | xBTC-USDC | PLACE |
HQJRFZ5rvbtppKYZpacHd4Qnq5sw5GptFmWRrUgFSsVS |
Oct 31, 2025 13:57:37 | +2,496.230109 | 223943473073280700691948735502 | xBTC-USDC | CANCEL |
3so5nheCyzztrFqWoRMq4K5Cq7nV91FHbP4rdpNfLmpM |
Oct 30, 2025 21:33:25 | -2,489.689131 | - | WAL-USDC | PLACE |
5dJ5p8a5FG8DCDo9qCEvCwpLXNzjKYVHzsKuHmkzxJFY |
Oct 30, 2025 21:31:43 | -2,498.105196 | - | xBTC-USDC | PLACE |
DqNzfAeyEtYr7Y3AbboyudBFzWpPVDDUdJq6if6cvyHF |
Oct 30, 2025 21:27:43 | -10,019.999723 | - | NS-USDC | PLACE |
Confirmed Cases (5 orders with fee losses)
Case 1: xBTC-USDC (0.0748% loss)
- PLACE:
AxNBpirqGkAbgeYRPkqk2pmvKsAEw9XVsvocJsBZ2i4A→ -10,022.004000 USDC - CANCEL:
2kMfBFaZiCKYsQeLGcab1bUJWUtKsHgh3jHoiRRDDn7f→ +10,014.502500 USDC - Loss: 7.501500 USDC (0.0748%)
- Order ID: 922521671144661420389868722210
Case 2: NS-USDC (0.1372% loss)
- PLACE:
GyJG5F9wkvinrU91HNeDMCpUz22V4Vd9445gBDS27bCb→ -10,007.427740 USDC - CANCEL:
9CD8Up2GEdp29dDCyBovkFa2t2fBy4QFVRqaDDVvfytK→ +9,993.695024 USDC - Loss: 13.732716 USDC (0.1372%)
- Order ID: 276885646993124443453501187
Case 3: NS-USDC (0.1217% loss)
- PLACE:
DqNzfAeyEtYr7Y3AbboyudBFzWpPVDDUdJq6if6cvyHF→ -10,019.999723 USDC - CANCEL:
4V6ryGtLbeHvyV13AMHC9dV9PAtYTME28nUU7EQ4N62J→ +10,007.800724 USDC - Loss: 12.198999 USDC (0.1217%)
- Order ID: 276885646993124443453506384
Case 4: xBTC-USDC (0.0751% loss)
- PLACE:
5dJ5p8a5FG8DCDo9qCEvCwpLXNzjKYVHzsKuHmkzxJFY→ -2,498.105196 USDC - CANCEL:
HQJRFZ5rvbtppKYZpacHd4Qnq5sw5GptFmWRrUgFSsVS→ +2,496.230109 USDC - Loss: 1.875087 USDC (0.0751%)
- Order ID: 223943473073280700691948735502
Case 5: xBTC-USDC (+0.1138% gain - anomaly)
- PLACE:
GdewvPDDHPMQAUrwhUA3JpM19of1y1d1QWcRZoZWFUTv→ -2,486.563265 USDC - CANCEL:
u2ypxcAsSvhX4ZbqYnHmaeSWhEHVJeRk4g5gRkisjnf→ +2,489.393798 USDC - Gain: +2.830533 USDC (+0.1138%)
- Order ID: 224312407954754891724268725825
- Note: This case resulted in a net gain. Reason unknown.
Case 6 (WAL-USDC): Order placed (3so5nheCyzztrFqWoRMq4K5Cq7nV91FHbP4rdpNfLmpM) but not yet canceled.
Summary Statistics
Total losses: 35.308302 USDC (excluding Case 5 anomaly)
Fee range: 0.0748% - 0.1372%
Trading pairs affected:
- xBTC-USDC: ~0.075% average (Cases 1, 4)
- NS-USDC: ~0.13% average (Cases 2, 3)
🔍 Additional Bug: Fee Variance May Correlate With Wallet Balance
The fee variance (0.0748% to 0.1372%) may be related to whether the wallet contained additional USDC beyond the order amount at placement time.
Observation:
- Same pair (NS-USDC) shows different fees: 0.1217% vs 0.1372%
- Wallet USDC balance varied across transactions
- Unable to confirm exact balance state per transaction
Implication: If confirmed, this suggests fees are incorrectly calculated based on total wallet balance rather than order size alone. This would be a second distinct bug beyond charging fees on unexecuted orders.
Expected vs Actual Behavior
Expected (per DeepBook V3 docs)
"Fees are charged ONLY upon execution, not upon placement"
For Post Only orders:
- Placement: No trading fees (only gas ~$0.002-0.003)
- Cancellation: No trading fees (only gas)
- No execution = No protocol fees
Actual (observed)
Orders that were:
- ✅ Never matched (Post Only cannot take)
- ✅ Never executed (0% fill confirmed)
- ✅ Canceled by user
Are charged 0.075%-0.137% fees, which is:
- 25x-45x higher than gas costs
- 3x-5.5x higher than documented max taker fee (0.025%)