# CVE-2026-34066: nimiq-blockchain: Peer-triggerable panic during history sync

Source: https://junglewise.ai/threats/cve-2026-34066-nimiq-blockchain-peer-triggerable-panic-during-history-sync  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-22. Updated: 2026-05-11  
License: CC BY 4.0 with a link back

CVE-2026-34066 · Severity: medium · CVSS 5.3 · Published 2026-04-22

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.

Technologies: [nimiq-blockchain (crates.io)](https://junglewise.ai/threats/technologies/nimiq-blockchain), [Nimiq Proof-Of-Stake](https://junglewise.ai/threats/technologies/nimiq-proof-of-stake). Vendors: [crates.io](https://junglewise.ai/threats/vendors/crates-io), [Nimiq](https://junglewise.ai/threats/vendors/nimiq).

## Quick answers

**Is CVE-2026-34066 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34066 being exploited in the wild.

**How severe is CVE-2026-34066?** Medium severity, with a CVSS score of 5.3, published 22 April 2026.

**Which products and versions are affected?** nimiq-blockchain (crates.io) <= 0.2.0, SEMVER:introduced=0,last_affected=0.2.0.

**Is there a fix for CVE-2026-34066?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2026-34066?** Check whether you run nimiq-blockchain (crates.io) or Nimiq Proof-Of-Stake at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- nimiq-blockchain (crates.io) <= 0.2.0, SEMVER:introduced=0,last_affected=0.2.0
- Nimiq Proof-Of-Stake

## Identifiers

- CVE-2026-34066
- GHSA-j99g-7rqw-q9jg

## References

- [https://api.github.com/users/1seal](https://api.github.com/users/1seal)
- [https://github.com/1seal](https://github.com/1seal)
- [https://api.github.com/users/1seal/gists%7B/gist_id%7D](https://api.github.com/users/1seal/gists%7B/gist_id%7D)
- [https://api.github.com/users/1seal/repos](https://api.github.com/users/1seal/repos)
- [https://avatars.githubusercontent.com/u/239602944?v=4](https://avatars.githubusercontent.com/u/239602944?v=4)
- [https://api.github.com/users/1seal/events%7B/privacy%7D](https://api.github.com/users/1seal/events%7B/privacy%7D)

## Related threats

- [Nimiq nimiq-blockchain off-by-one error in validity store](https://junglewise.ai/threats/cve-2026-46369-nimiq-nimiq-blockchain-off-by-one-error-in-validity-store)
- [Nimiq core-rs-albatross denial of service via RequestBatchSet panic](https://junglewise.ai/threats/cve-2026-46543-nimiq-core-rs-albatross-denial-of-service-via-requestbatchset)
- [nimiq-transaction: UpdateValidator transactions allows voting key change without proof-of-knowledge](https://junglewise.ai/threats/cve-2026-34068-nimiq-transaction-updatevalidator-transactions-allows-voting-key)
- [nimiq-transaction: Panic via `HistoryTreeProof` length mismatch](https://junglewise.ai/threats/cve-2026-34067-nimiq-transaction-panic-via-historytreeproof-length-mismatch)
- [nimiq-primitives: Node crash due to missing interlink validation in election macro block proposals](https://junglewise.ai/threats/cve-2026-34065-nimiq-primitives-node-crash-due-to-missing-interlink-validation)