# CVE-2026-34067: nimiq-transaction vulnerable to panic via `HistoryTreeProof` length mismatch

> A malicious peer can crash the application by sending a malformed transaction proof, requiring an upgrade to the fixed library version.

- **Severity:** Low 3.1 (`CVSS:3.1/AV:N/AC:H/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:** 22 Apr 2026
- **Updated:** 23 Apr 2026
- **Also known as:** GHSA-264v-m8fm-76jm

## What is CVE-2026-34067?

CVE-2026-34067 is a low-severity denial of service vulnerability in nimiq-transaction, published on 22 Apr 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-transaction provides the transaction primitive to be used in Nimiq's Rust implementation. Prior to version 1.3.0, `HistoryTreeProof::verify` panics on a malformed proof where `history.len() != positions.len()` due to `assert_eq!(history.len(), positions.len())`. The proof object is derived from untrusted p2p responses (`ResponseTransactionsProof.proof`) and is therefore attacker-controlled at the network boundary until validated. A malicious peer could trigger a crash by returning a crafted inclusion proof with a length mismatch. The patch for this vulnerability is included as part of v1.3.0. No known workarounds are available.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2026-34067?

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


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

Products: Nimiq Nimiq Proof-of-Stake.

## How do I fix CVE-2026-34067?

No fix has been published for CVE-2026-34067 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34067 being exploited?

There is no known exploitation of CVE-2026-34067 in the wild and no public exploit code.

## Other vulnerabilities in nimiq-transaction

- [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-2026-40093](https://insights.sbomify.com/CVE-2026-40093/): nimiq-blockchain is missing a wall-clock upper bound on block timestamps (high 8.1)
- [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)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34067 and fix it if it is affected.

What it is: CVE-2026-34067 is a low-severity denial of service vulnerability in nimiq-transaction, published on 22 Apr 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-2026-34067 in the wild and no public exploit code.

Affected packages and fixed versions:
- nimiq-transaction (crates.io): affected all versions up to 0.2.0; no fix listed
- nimiq-transaction (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-2026-34067/ (Markdown: https://insights.sbomify.com/CVE-2026-34067/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34067
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34067
- OSV: https://osv.dev/vulnerability/CVE-2026-34067

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34067/
Summaries are generated and may contain mistakes; the official description above is the record.