# CVE-2026-46539: nimiq-primitives: BlockInclusionProof interlink issue when hops are empty

> Attackers can forge block inclusion proofs by exploiting a logic flaw that skips verification when hop lists are empty, affecting Nimiq core-rs-albatross users.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Jun 2026
- **Updated:** 10 Jun 2026
- **Also known as:** GHSA-799f-29jm-gr6c

## What is CVE-2026-46539?

CVE-2026-46539 is a medium-severity vulnerability in nimiq core-rs-albatross, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Nimiq is a Rust implementation of the Nimiq Proof-of-Stake protocol based on the Albatross consensus algorithm. Prior to version 1.4.0, a logic flaw in BlockInclusionProof::is_block_proven causes the function to return true without performing any cryptographic verification when get_interlink_hops yields an empty hop list. This occurs when the target block is at the election block position immediately preceding the election head's epoch. An attacker providing transaction inclusion proofs can forge a MacroBlock header for that epoch position and have it accepted as "proven" without any hash or signature verification. This issue has been patched in version 1.4.0.

Weakness: CWE-345 (Insufficient Verification of Data Authenticity)

## Which versions are affected by CVE-2026-46539?

2 open source packages ship an affected version, including nimiq-primitives.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `nimiq-primitives` | crates.io | All versions to 0.2.0 | None |
| `nimiq-primitives` | crates.io | All versions to 0.2.0 | None |

## How do I fix CVE-2026-46539?

No fix has been published for CVE-2026-46539 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-46539 being exploited?

There is no known exploitation of CVE-2026-46539 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46539 and fix it if it is affected.

What it is: CVE-2026-46539 is a medium-severity vulnerability in nimiq core-rs-albatross, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-46539 in the wild and no public exploit code.

Affected packages and fixed versions:
- nimiq-primitives (crates.io): affected all versions up to 0.2.0; no fix listed
- nimiq-primitives (crates.io): affected all versions up to 0.2.0; 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-2026-46539/ (Markdown: https://insights.sbomify.com/CVE-2026-46539/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46539
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46539
- OSV: https://osv.dev/vulnerability/CVE-2026-46539

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46539/
Summaries are generated and may contain mistakes; the official description above is the record.