CVE-2023-42806: Iohk Hydra

Medium severity, CVSS 6.5. EPSS: 0.5% chance of exploitation in the next 30 days.

Hydra is the layer-two scalability solution for Cardano. Prior to version 0.13.0, not signing and verifying `$\mathsf{cid}$` allows an attacker (which must be a participant of this head) to use a snapshot from an old head instance with the same participants to close the head or contest the state with it. This can lead to an incorrect distribution of value (= value extraction attack; hard, but possible) or prevent the head to finalize because the value available is not consistent with the closed utxo state (= denial of service; easy). A patch is planned for version 0.13.0. As a workaround, rotate keys between heads so not to re-use keys and not result in the same multi-signature participants.

Affected products

• Iohk Hydra: before 0.13.0 (fixed in 0.13.0)

Published 2023-09-21. Last modified 2026-06-17.