# CVE-2026-40093: nimiq-blockchain is missing a wall-clock upper bound on block timestamps

> A malicious validator can set future block timestamps to inflate monetary supply, affecting reward calculations in the Nimiq blockchain library.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Apr 2026
- **Updated:** 13 Apr 2026
- **Also known as:** GHSA-49xc-52mp-cc9j

## What is CVE-2026-40093?

CVE-2026-40093 is a high-severity vulnerability in nimiq core-rs-albatross, published on 9 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

nimiq-blockchain provides persistent block storage for Nimiq's Rust implementation. In 1.3.0 and earlier, block timestamp validation enforces that timestamp >= parent.timestamp for non-skip blocks and timestamp == parent.timestamp + MIN_PRODUCER_TIMEOUT for skip blocks, but there is no visible upper bound check against the wall clock. A malicious block-producing validator can set block timestamps arbitrarily far in the future. This directly affects reward calculations via Policy::supply_at() and batch_delay() in blockchain/src/reward.rs, inflating the monetary supply beyond the intended emission schedule.

Weakness: CWE-1284 (Improper Validation of Specified Quantity in Input)

## Which versions are affected by CVE-2026-40093?

2 open source packages ship an affected version, including nimiq-blockchain. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `nimiq-blockchain` | crates.io | All versions to 1.3.0 | None |
| `nimiq-blockchain` | crates.io | All versions to 1.3.0 | None |

Products: Nimiq Nimiq Proof-of-Stake.

## How do I fix CVE-2026-40093?

No fix has been published for CVE-2026-40093 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-40093 being exploited?

There is no known exploitation of CVE-2026-40093 in the wild and no public exploit code.

## Other vulnerabilities in nimiq core-rs-albatross

- [CVE-2026-33471](https://insights.sbomify.com/CVE-2026-33471/): nimiq-block has skip block quorum bypass via out-of-range BitSet indices & u16 truncation (critical 9.6)
- [CVE-2026-34063](https://insights.sbomify.com/CVE-2026-34063/): network-libp2p: Peer can crash the node by opening discovery protocol substream twice (high 7.5)
- [CVE-2026-34065](https://insights.sbomify.com/CVE-2026-34065/): nimiq-primitives: Node crash due to missing interlink validation in election macro block proposals (high 7.5)
- [CVE-2026-32605](https://insights.sbomify.com/CVE-2026-32605/): Nimiq: Remote crash via off-by-one signer bounds check in proposal buffer (high 7.5)
- [CVE-2026-33184](https://insights.sbomify.com/CVE-2026-33184/): nimiq/core-rs-albatross: Discovery handshake limit could underflow and later provoke a deterministic overflow panic (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40093 and fix it if it is affected.

What it is: CVE-2026-40093 is a high-severity vulnerability in nimiq core-rs-albatross, published on 9 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-40093 in the wild and no public exploit code.

Affected packages and fixed versions:
- nimiq-blockchain (crates.io): affected all versions up to 1.3.0; no fix listed
- nimiq-blockchain (crates.io): affected all versions up to 1.3.0; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-40093/ (Markdown: https://insights.sbomify.com/CVE-2026-40093/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40093
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40093
- OSV: https://osv.dev/vulnerability/CVE-2026-40093

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40093/
Summaries are generated and may contain mistakes; the official description above is the record.