CVE-2026-34069: Nimiq nimiq-consensus panic in RequestMacroChain handler

CVE-2026-34069 · Severity: medium · CVSS 5.3 · Published 2026-04-14

A vulnerability in the Nimiq blockchain consensus library allows an unauthenticated attacker to crash a node by sending a specially crafted network message. This results in a denial-of-service (DoS) condition, potentially disrupting the node's ability to participate in the blockchain network and process transactions. The issue affects the Albatross implementation of the Nimiq protocol.

Technologies: Nimiq Proof-Of-Stake. Vendors: crates.io, Nimiq.

Quick answers

Is CVE-2026-34069 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-34069 being exploited in the wild.
How severe is CVE-2026-34069?
Medium severity, with a CVSS score of 5.3, published 14 April 2026.
Which products and versions are affected?
nimiq-consensus (crates.io) <= 1.2.2, SEMVER:introduced=0,last_affected=1.2.2; Nimiq Consensus <= 1.2.2.
Is there a fix for CVE-2026-34069?
A patch was published on 2026-04-13: Fix released in version 1.3.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-34069 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-34069?
Check whether you run nimiq-consensus (crates.io), Nimiq Consensus 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

A reachable assertion (CWE-617) exists in the `RequestMacroChain::handle` function of the `nimiq-consensus` crate. An unauthenticated P2P peer can send a `RequestMacroChain` message where the first locator hash on the victim's main chain corresponds to a micro block rather than a macro block. The handler fails to validate the block type before calling `get_macro_blocks()`, which subsequently triggers an `.unwrap()` on a `BlockchainError::BlockIsNotMacro` error, causing the task to panic. This vulnerability is fixed in version 1.3.0 of the Nimiq core-rs-albatross repository.

Affected products

  • Nimiq nimiq-consensus <= 1.2.2

Identifiers

  • CVE-2026-34069
  • GHSA-48m6-486p-9j8p

Timeline

  • 2026-04-11: disclosed: Vulnerability reported to Nimiq
  • 2026-04-13: advisory: GitHub Advisory GHSA-48m6-486p-9j8p published
  • 2026-04-13: patched: Fix released in version 1.3.0

References

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