# CVE-2026-40093: Nimiq nimiq-blockchain missing upper bound on block timestamps

Source: https://junglewise.ai/threats/cve-2026-40093-nimiq-nimiq-blockchain-missing-upper-bound-on-block-timestamps  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-09. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2026-40093 · Severity: critical · CVSS 9.1 · Published 2026-04-09

Nimiq Blockchain is a Rust-based implementation of the Nimiq cryptocurrency protocol. A vulnerability in how the system validates block times allows malicious participants to submit blocks with timestamps set far into the future. This can be exploited to manipulate the network's reward system, leading to the unauthorized creation of new currency and undermining the integrity of the blockchain's economic model.

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-2026-40093 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-40093 being exploited in the wild.

**How severe is CVE-2026-40093?** Critical severity, with a CVSS score of 9.1, published 9 April 2026.

**Which products and versions are affected?** nimiq-blockchain (crates.io) <= 1.3.0, SEMVER:introduced=0,last_affected=1.3.0.

**Is there a fix for CVE-2026-40093?** 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.

**How is CVE-2026-40093 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-40093?** 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.

## Technical details

The nimiq-blockchain library lacks a wall-clock upper bound check during block timestamp validation. While it ensures timestamps are greater than or equal to the parent block, it does not verify them against the current real-world time. A malicious validator can produce blocks with arbitrary future timestamps, which directly impacts reward calculations in 'blockchain/src/reward.rs' via 'Policy::supply_at()' and 'batch_delay()'. This allows for the inflation of the monetary supply beyond the protocol's defined emission schedule. The vulnerability is present in versions up to and including 1.3.0.

## Affected products

- Nimiq nimiq-blockchain <= 1.3.0

## Identifiers

- CVE-2026-40093
- GHSA-49xc-52mp-cc9j

## Timeline

- 2026-04-09: disclosed
- 2026-04-10: advisory

## References

- [https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-49xc-52mp-cc9j](https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-49xc-52mp-cc9j)

## 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-blockchain: Peer-triggerable panic during history sync](https://junglewise.ai/threats/cve-2026-34066-nimiq-blockchain-peer-triggerable-panic-during-history-sync)