Incident Overview
On March 11, 2026, DBXen suffered a $150K exploit across Ethereum and BSC when an attacker exploited an inconsistent sender identity vulnerability in ERC2771 meta-transactions, where burnBatch() used _msgSender() (actual user) while the callback onTokenBurned() used msg.sender() (forwarder), breaking reward accounting logic and allowing excess fund withdrawal.
The vulnerability stemmed from inconsistent sender identity handling in DBXen's meta-transaction implementation. In the burnBatch() function, the gasWrapper() modifier updated state using _msgSender() which correctly identified the actual user, but the subsequent onTokenBurned() callback used msg.sender() which identified the forwarder contract instead. This caused accCycleBatchesBurned to be recorded for the user while lastActiveCycle was incorrectly updated for the forwarder. When claimFees() and claimRewards() executed updateStats() for the user, the contract detected that accCycleBatchesBurned[user] had increased but lastActiveCycle[user] had not, incorrectly assuming unprocessed burned batches existed. This state inconsistency caused the contract to miscalculate rewards and fees, allowing the attacker to withdraw significantly more funds than entitled. The attack was executed across both Ethereum and BSC chains.
Blockchain Data Reference
Exploit txs:
https://etherscan.io/tx/0x914a5af7…08bc37
https://bscscan.com/tx/0xe66e5458…65d366
Incident Report
Protocol Information
Market Context at Time of Hack
What the Attacker Needed to Succeed
Understanding the prerequisites for this type of attack helps auditors identify protocols that are most at risk and helps developers build better defenses.
What Auditors Should Check
If you're auditing a protocol with similar architecture to DBXen, these are the critical security checks that could have prevented this incident (March 2026).
- Verify all logic paths related to Access Control are guarded by proper access controls and input validation - see the Access Control Attacks attack class for patterns
- Review privileged functions (owner, admin, governance) for potential abuse vectors - centralization risks should be documented and bounded with timelocks or multi-sigs
Master these auditing techniques with hands-on labs and real exploit scenarios in the Smart Contract Hacking course.
Free TrialRelated Attack Classes
The technique used in this hack maps to these vulnerability classes in our security curriculum:
Sources & References
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