CVE-2023-42449

What it is

Hydra is the two-layer scalability solution for Cardano. Prior to version 0.13.0, it is possible for a malicious head initializer to extract one or more PTs for the head they are initializing due to incorrect data validation logic in the head token minting policy which then results in an flawed check for burning the head ST in the `initial` validator. This is possible because it is not checked in `HeadTokens.hs` that the datums of the outputs at the `initial` validator are equal to the real head ID, and it is also not checked in the `off-chain code`. During the `Initial` state of the protocol, if the malicious initializer removes a PT from the Hydra scripts it becomes impossible for any other participant to reclaim any funds they have attempted to commit into the head, as to do so the Abort transaction must burn all the PTs for the head, but they cannot burn the PT which the attacker controls and so cannot satisfy this requirement. That means the initializer can lock the other participants committed funds forever or until they choose to return the PT (ransom). The malicious initializer can also use the PT to spoof that they have committed a particular TxO when progressing the head into the `Open` state. For example, they could say they committed a TxO residing at their address containing 100 ADA, but in fact this 100 ADA was not moved into the head, and thus in order for an other participant to perform the fanout they will be forced to pay the attacker the 100 ADA out of their own funds, as the fanout transaction must pay all the committed TxOs (even though the attacker did not really commit that TxO). They can do this by placing the PT in a UTxO with a well-formed `Commit` datum with whatever contents they like, then use this UTxO in the `collectCom` transaction. There may be other possible ways to abuse having control of a PT. Version 0.13.0 fixes this issue.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data tampering, service disruption.

Exploit odds

1.1% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2023-10-04 20:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 06:23 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.1% in the next 30 days (EPSS).
• Severity: 8.1 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2023-10-04 20:15 UTC

Last modified

2026-06-17 06:23 UTC

Exploit probability

1.1% · EPSS, next 30 days

Weakness

CWE-20 · Improper input validation

Record status

Modified

Affected

• Iohk Hydra < 0.13.0

Attack profile CVSS 3.1 · 8.1

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2023-42449.md and follow it. Check whether this project is affected by CVE-2023-42449. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge