Tender Finance Hack

TOTAL LOST $1.6M
Medium Outdated Oracle Exploit arbitrum

Summarize with AI

Affected Chain arbitrum Incident surface
Recovered - No recovery reported
All-Time Rank #717 By amount stolen
Auditors 1 Prior security audit

Incident Overview

Tender Finance is an innovative open-source decentralized protocol for borrowing and lending. It will support whole-portfolio collateralization, starting with GMX and GLP, and a novel mechanism for collateralizing long-tail assets.

Incident Report

Protocol / Project Tender Finance
Date of Incident
Affected Chain(s) arbitrum
Attack Technique Outdated Oracle Exploit
Classification Ecosystem
Primary Source View Post-Mortem

Protocol Information

Protocol Type Lending
Smart Contract Language Solidity
Official Website xend.finance/
Protocol Twitter/X @tender_fi

Market Context at Time of Hack

Token Categories
DeFi Smart Contracts Ethereum Ecosystem DAO Maker Exnetwork Capital Portfolio Polygon Ecosystem Arbitrum Ecosystem BNB Chain Ecosystem

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.

Technical Knowledge Deep understanding of outdated oracle exploit and Solidity and EVM internals
Capital Required Seed capital to cover gas and initial position setup
On-Chain Access Ability to interact with arbitrum smart contracts and deploy a custom exploit contract
Protocol Analysis Identification of the exploitable vulnerability in Tender Finance's contract logic - root cause: ecosystem
Execution Speed Precise transaction ordering and timing to exploit the vulnerability within a single atomic block
Obfuscation Plan A strategy to launder and move stolen funds - typically through mixers, cross-chain bridges, or decentralized DEX swaps to resist tracing

What Auditors Should Check

Could this have been caught in audit? Yes — skilled auditors routinely flag Outdated Oracle Exploit vulnerabilities in code review
Audited by Audit Report 1 — still lost $1.6M. Prior audits don't guarantee safety, especially after post-audit code changes.

If you're auditing a protocol with similar architecture to Tender Finance, these are the critical security checks that could have prevented this incident (March 2023).

  • Verify all logic paths related to Outdated Oracle Exploit are guarded by proper access controls and input validation - see the Oracle Manipulation & Price Manipulation attack class for patterns
  • Audit oracle price feeds for manipulation risks - ensure time-weighted average prices (TWAPs) or multi-source aggregators are used, not spot prices
  • Review privileged functions (owner, admin, governance) for potential abuse vectors - centralization risks should be documented and bounded with timelocks or multi-sigs

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Security Audit History

Related Attack Classes

The technique used in this hack maps to these vulnerability classes in our security curriculum:

See all Oracle Manipulation & Price Manipulation examples →

Sources & References

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