# NUT-14 allows cashu tokens to be created with a preimage hash. However, nutshell (cashubtc/nuts) before 0.18.0 do not validate the size of preimage when the token is spent. The preimage is stored b...

Advisory record · `PYSEC-2025-89`

- **Identifiers:** `PYSEC-2025-89` · `CVE-2025-65548`
- **State:** Confirmed
- **Severity:** CVSS 9.1 Critical
- **Critical:** Yes: CVSS 9+
- **Weakness (CWE):** [CWE-1284](https://cwe.mitre.org/data/definitions/1284.html)
- **Tags:** [CWE-1284](https://agentprime.io/advisories/tag/cwe-1284.md)
- **Published:** 8 Dec 2025
- **Updated:** 20 May 2026
- **Reviewed by a person:** No

Published by OSV at 8 Dec 2025, 19:15 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Critical

Critical, because:

- CVSS score 9.1: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected packages

- `cashu` (PyPI): affected `<0.18.0`; fixed in `0.18.0`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 9.1 Critical, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`, from OSV

- **CISA KEV:** Not listed.
- **EPSS:** 0.0045, the 39th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of OSV, published 8 Dec 2025. New records show when each source confirmed them.

## Sources

- [OSV: PYSEC-2025-89](https://osv.dev/vulnerability/PYSEC-2025-89)
- <https://delvingbitcoin.org/t/public-disclosure-denial-of-service-using-htlc-in-cashu/2090>
- <https://preimage007.github.io/>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/PYSEC-2025-89>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/PYSEC-2025-89/>. Everything for agents: <https://agentprime.io/llms.txt>.