HermesVault Hack

TOTAL LOST $30K
Low Other

Summarize with AI

ChatGPT Perplexity Claude Grok
Affected Chain 2026 Incident surface
Recovered - No recovery reported
All-Time Rank #1835 By amount stolen
Protocol Type Exploit/Other Target category

Incident Overview

Quick Summary

On May 20, 2026, the Algorand-based privacy protocol HermesVault was exploited for approximately 261,000 ALGO (~$29,500). HermesVault has since disabled deposits and permanently retired the protocol.

Details of the Exploit

The exploit bypassed HermesVault’s privacy guarantees by targeting the "LogicSig" (Logic Signature) verification script. While the core zk-circuits functioned as intended, a vulnerability in the guard logic against rekeying allowed the attacker to rekey the withdrawal verifier contract. By doing so, the attacker gained unauthorized control over the contract and was able to execute withdrawals, completely circumventing the zk-proof validation path.

The attacker utilized a rekey transaction to hijack the verifier, followed by a withdrawal transaction to drain the funds. The protocol team identified the flaw, patched the underlying algoplonk library to prevent similar rekeying attacks in the future, and initiated an immediate refund process. Because the protocol has retired, the team is manually verifying claims from users who can prove ownership of their deposit addresses via secret notes.

Block Data Reference

Attacker Address: 2PYF5VFHZYXR7NDXHEPVNJJ73FKTXKTQ3TAUH6ZIIEEL73MCTXUN4GQEL4

Exploit Transactions:

Rekeying: PPYN7EUFUOMGKHJJSZG2DDYMSUIF66LV2YOXMSEJGLVUOYLJCSVQ

Withdrawal: ZBNGF7QOQ6MZZP2PUXPK5VOLZSQBU3QTEYW6UVX4J2JSU2ACEQ7Q

Incident Report

Protocol / Project HermesVault
Date of Incident
Attack Technique Other
Classification Other
Primary Source View Post-Mortem #1 View Post-Mortem #2

Protocol Information

Protocol Type Exploit/Other
Official Website hermesvault.org/
Team Anonymous
Source Code Unverified

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 other and Solidity and EVM internals
Capital Required Seed capital to cover gas and initial position setup
On-Chain Access Ability to interact with smart contracts and deploy a custom exploit contract
Protocol Analysis Identification of the exploitable vulnerability in HermesVault's contract logic - root cause: other
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? Likely — with a thorough Other audit checklist and test coverage

If you're auditing a protocol with similar architecture to HermesVault, these are the critical security checks that could have prevented this incident (May 2026).

  • Verify all logic paths related to Other are guarded by proper access controls and input validation
  • 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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