# CVE-2026-40094: nimiq-blockchain: network-libp2p untrusted peer can crash address book via empty peer contact addresses

> An untrusted peer can crash the Nimiq blockchain node by submitting a peer contact with an empty address list, causing a panic during address book generation.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L`)
- **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 available:** No
- **Published:** 20 May 2026
- **Updated:** 21 May 2026
- **Also known as:** GHSA-c45m-6x25-3cjq

## What is CVE-2026-40094?

CVE-2026-40094 is a medium-severity denial of service vulnerability in nimiq core-rs-albatross, published on 20 May 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. In versions 1.3.0 and prior, network-libp2p discovery accepts signed PeerContact updates from untrusted peers and stores them in a peer contact book, eventually leading to address book crash. A PeerContact can legally contain an empty addresses list (no intrinsic validation enforces non-empty). Later, PeerContactBook::known_peers builds an address book by taking addresses.first().expect("every peer should have at least one address"). If the attacker has inserted a signed peer contact with addresses=[], any call to get_address_book (RPC/web client) can panic and crash the node/RPC task depending on panic settings. This issue has been fixed in version 1.4.0.

Weakness: CWE-754 (Improper Check for Unusual or Exceptional Conditions)

## Which versions are affected by CVE-2026-40094?


## How do I fix CVE-2026-40094?

No fix has been published for CVE-2026-40094 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-40094 being exploited?

There is no known exploitation of CVE-2026-40094 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40094 and fix it if it is affected.

What it is: CVE-2026-40094 is a medium-severity denial of service vulnerability in nimiq core-rs-albatross, published on 20 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-40094 in the wild and no public exploit code.

Affected product: nimiq core-rs-albatross. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-40094/ (Markdown: https://insights.sbomify.com/CVE-2026-40094/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40094
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40094
- OSV: https://osv.dev/vulnerability/CVE-2026-40094

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40094/
Summaries are generated and may contain mistakes; the official description above is the record.