CVE-2026-34066 is a medium-severity (CVSS 5.3) Improper Input Validation vulnerability in nimiq-blockchain. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.
nimiq-blockchain: Peer-triggerable panic during history sync
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34066.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
nimiq-blockchainReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | nimiq-blockchain | all versions | No fix |
Affected Products
nimiq proof-of-stakenimiqDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nimiq-blockchain, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
The records we use list no patched version of nimiq-blockchain for CVE-2026-34066. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-34066 in your dependencies?
Find it across crates.io, including transitive dependencies.