CVE-2026-33471

nimiq-block contains block primitives to be used in Nimiq's Rust implementation. `SkipBlockProof::verify` computes its quorum check using `BitSet.len()`, then iterates `BitSet` indices and casts each `usize` index to `u16` (`slot as u16`) for slot lookup. Prior to version 1.3.0, if an attacker can get a `SkipBlockProof` verified where `MultiSignature.signers` contains out-of-range indices spaced by 65536, these indices inflate `len()` but collide onto the same in-range `u16` slot during aggregation. This makes it possible for a malicious validator with far fewer than `2f+1` real signer slots to pass skip block proof verification by multiplying a single BLS signature by the same factor. The patch for this vulnerability is included as part of v1.3.0. No known workarounds are available.

CVSS 3.1

9.6CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H

EPSS

0.2% chance of exploitation in the next 30 days; higher than 12% of CVEs (scores of 2026-10-26)

CWEs

CWE-20, CWE-190, CWE-345, CWE-1284

Published

2026-04-22

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Affected

• nimiq:nimiq_proof-of-stake

Packages (OSV)

References

• https://github.com/nimiq/core-rs-albatross/commit/d02059053181ed8ddad6b59a0adfd661ef5cd823
• https://github.com/nimiq/core-rs-albatross/releases/tag/v1.3.0
• https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-6973-8887-87ff

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