# CVE-2026-34066

> Vulnerability · severity: **MEDIUM** (CVSS 5.3).

## Description

nimiq-blockchain provides persistent block storage for Nimiq's Rust implementation. Prior to version 1.3.0, `HistoryStore::put_historic_txns` uses an `assert!` to enforce invariants about `HistoricTransaction.block_number` (must be within the macro block being pushed and within the same epoch). During history sync, a peer can influence the `history: &[HistoricTransaction]` input passed into `Blockchain::push_history_sync`, and a malformed history list can violate these invariants and trigger a panic. `extend_history_sync` calls `this.history_store.add_to_history(..)` before comparing the computed history root against the macro block header (`block.history_root()`), so the panic can happen before later rejection checks run. The patch for this vulnerability is included as part of v1.3.0. No known workarounds are available.

## Key facts

- **CVE ID:** CVE-2026-34066
- **Published:** 2026-04-22
- **CVSS severity:** MEDIUM
- **CVSS base score:** 5.3
- **CWE codes:** CWE-20, CWE-617, CWE-754

## Affected products

- `nimiq:nimiq_proof-of-stake`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34066

## Citation

> AI Analytics. CVE-2026-34066. Retrieved 2026-07-23 from https://api.ai-analytics.org/cve/CVE-2026-34066. Derived from NIST NVD. Licensed CC0.

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