CVE-2026-34066 nimiq-blockchain: Peer-triggerable panic during history sync
A remote peer can trigger a panic in the nimiq-blockchain library during history sync, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-34066?
CVE-2026-34066 is a medium-severity denial of service vulnerability in nimiq-blockchain, published on 22 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2026-34066?
2 open source packages ship an affected version, including nimiq-blockchain. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
nimiq-blockchain crates.io | All versions to 0.2.0 | None |
nimiq-blockchain crates.io | All versions to 0.2.0 | None |
Products include Nimiq Nimiq Proof-of-Stake.
How do I fix CVE-2026-34066?
No fix has been published for CVE-2026-34066 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-34066 being exploited?
There is no known exploitation of CVE-2026-34066 in the wild and no public exploit code.
Other vulnerabilities in nimiq-blockchain
- CVE-2026-33471 nimiq-block has skip block quorum bypass via out-of-range BitSet indices & u16 truncation
- CVE-2026-40093 nimiq-blockchain is missing a wall-clock upper bound on block timestamps
- CVE-2026-34063 network-libp2p: Peer can crash the node by opening discovery protocol substream twice
- CVE-2026-34065 nimiq-primitives: Node crash due to missing interlink validation in election macro block proposals
- CVE-2026-32605 Nimiq: Remote crash via off-by-one signer bounds check in proposal buffer
Sources
Also known as GHSA-j99g-7rqw-q9jg.