Unverified Contract uniswapV3Callback Lacking Access Control
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On August 28th, 2025, an unverified smart contract was deployed on the Base blockchain containing a critical vulnerability: the uniswapV3SwapCallback function lacked proper access control. This allowed an attacker to exploit the contract using a delegatecall to another contract, resulting in a reported loss of approximately $88.9K. The incident was first analyzed and reported by TenArmor and researcher Weilin (William) Li, and later included in Blockthreat’s Week 36 report. The responsible project remains unidentified, and there is currently no indication of an ongoing investigation or recovery efforts.[1][2][3][4][5][6][7][8][9]
About Unverified Contract
An unverified smart contract was launched on the Base blockchain on August 28th, 2025.
This invokes code in another smart contract via a delegatecall.
The Reality
Unfortunately, the smart contract was launched with a vulnerability where the uniswapV3Callback function lacked access control.
What Happened
An unverified smart contract on the Base blockchain was exploited due to a missing access control in the uniswapV3SwapCallback function, resulting in a reported loss of $88.9K.
| Date | Event | Description |
|---|---|---|
| August 28th, 2025 3:35:11 PM MDT | Victim Smart Contract Launched | The victim smart contract is first launched on the Base blockchain. |
| August 29th, 2025 5:55:05 AM MDT | Delegated Smart Contract Launched | The smart contract starting with 0x1d9e is launched, containing a vulnerability due to the lack of access control on uniswapV3Callback. |
| September 1st, 2025 12:38:27 AM MDT | Base Attack Transaction | The attack is accepted into the Base blockchain. |
| September 1st, 2025 1:13:00 AM MDT | TenArmor Tweet Posted | TenArmor posts a tweet with details about the xploit. |
Technical Details
According to an initial analysis by TenArmor, "[i]t appears that the uniswapV3SwapCallback function of the contract 0x1d9e lacks access control, which was exploited by the attacker."
Total Amount Lost
TenArmor has reported that there was "an approximately loss of $88.9K".
The total amount lost has been estimated at $89,000 USD.
Immediate Reactions
The incident was reported by TenArmor and researcher Weilin (William) Li.
Ultimate Outcome
It appears that the incident was included in the Blockthreat report for Week 36 of 2025.
Total Amount Recovered
There is limited information available about the smart contract, and no suggestion that any recovery is presently being attempted.
There do not appear to have been any funds recovered in this case.
Ongoing Developments
It's unclear which project is behind this address, and whether any investigation is underway.
Individual Prevention Policies
No specific policies for individual prevention have yet been identified in this case.
For the full list of how to protect your funds as an individual, check our Prevention Policies for Individuals guide.
Platform Prevention Policies
Policies for platforms to take to prevent this situation have not yet been selected in this case.
For the full list of how to protect your funds as a financial service, check our Prevention Policies for Platforms guide.
Regulatory Prevention Policies
No specific regulatory policies have yet been identified in this case.
For the full list of regulatory policies that can prevent loss, check our Prevention Policies for Regulators guide.
References
- ↑ TenArmor - "Our system has detected a suspicious attack involving #unverified contract 0x46cbe on #BASE, resulting in an approximately loss of $88.9K." - Twitter/X (Accessed Sep 19, 2025)
- ↑ Attack Transaction - BaseScan (Accessed Sep 19, 2025)
- ↑ Weilin (William) Li - "yet another uniswapV3Callback lacking access control." - Twitter/X (Accessed Sep 19, 2025)
- ↑ BlockThreat - Week 36, 2025 (Accessed Sep 19, 2025)
- ↑ Transaction details - Blockscout (Accessed Sep 19, 2025)
- ↑ Victim Smart Contract - BaseScan (Accessed Sep 19, 2025)
- ↑ Victim Smart Contract Creation Transaction - BaseScan (Accessed Sep 19, 2025)
- ↑ Vulnerable Smart Contract - BaseScan (Accessed Sep 19, 2025)
- ↑ Creation Of Delegated Smart Contract - BaseScan (Accessed Sep 19, 2025)