Description
Hydra is a layer-two scalability solution for Cardano. Prior to 2.1.0, the `Claim` branch in `hydra-plutus/validators/deposit.ak` checks only that `datum.head_id` matches the attacker-controlled `redeemer.currencySymbol` and that the transaction is valid before the deposit deadline. It neither requires spending the Head state-token UTxO in the same transaction nor constrains outputs. After a deposit made through `POST /commit` is confirmed, any third party able to build a Cardano transaction can observe and consume the pending deposit UTxO before its deadline and redirect the assets to an arbitrary address. A standalone deposit spend invokes no Head validator, bypassing its safety checks; historical head-ID binding and the Aiken rewrite retained this missing invariant. The default deadline is three times depositPeriod, so the described attack applies to pending deposits before that deadline. This issue is fixed in version 2.1.0.
Published: 2026-10-30
Score: 8.2 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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History

Fri, 30 Oct 2026 18:45:00 +0000

Type Values Removed Values Added
Description Hydra is a layer-two scalability solution for Cardano. Prior to 2.1.0, the `Claim` branch in `hydra-plutus/validators/deposit.ak` checks only that `datum.head_id` matches the attacker-controlled `redeemer.currencySymbol` and that the transaction is valid before the deposit deadline. It neither requires spending the Head state-token UTxO in the same transaction nor constrains outputs. After a deposit made through `POST /commit` is confirmed, any third party able to build a Cardano transaction can observe and consume the pending deposit UTxO before its deadline and redirect the assets to an arbitrary address. A standalone deposit spend invokes no Head validator, bypassing its safety checks; historical head-ID binding and the Aiken rewrite retained this missing invariant. The default deadline is three times depositPeriod, so the described attack applies to pending deposits before that deadline. This issue is fixed in version 2.1.0.
Title Hydra: Deposit Claim omits Head state-token spending requirement
Weaknesses CWE-862
References
Metrics cvssV4_0

{'score': 8.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N'}


Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-30T18:30:20.005Z

Reserved: 2026-07-13T14:16:29.572Z

Link: CVE-2026-62162

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-10-30T19:18:32.630

Modified: 2026-10-30T19:39:14.897

Link: CVE-2026-62162

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-30T19:45:14Z

Weaknesses