CVE-2023-42449
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedHydra 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysisThe application accepts input without confirming it is well-formed or within expected bounds, so malformed data can push the program into states its author never anticipated. Attackers probe these gaps to trigger crashes, bypass logic, or feed tainted values into more dangerous operations downstream. Remediating it well means validating and normalising every input at the boundary against a strict allow-list — not merely filtering known-bad values.
General guidance for the improper input validation class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 0.13.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped0.13.0
0.13.0
- Verify current Hydra version using `hydra-node --version` or checking project dependencies
- Stop any running Hydra nodes or services
- Update to version 0.13.0 by updating the project dependency (e.g., via Nix flake, cabal.project, or Docker image tag)
- Verify successful installation with `hydra-node --version`
- Restart Hydra nodes with the updated version
Generated from the published advisory — verify against the referenced sources before acting.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-42449 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-42449 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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