CVE-2026-33471

CRITICAL EPSS 12.1%
Published Apr 22, 20262mo ago · Modified Jun 17, 20262w ago
9.6 CVSS 3.1
Critical
Find Similar
Published Apr 22, 2026 2mo ago
Last Modified Jun 17, 2026 2w ago

Description

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 Details

Base Score
9.6
Exploitability
3.1
Impact
5.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Changed
Confidentiality None
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
12.1% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 4

CWE-1284
CWE-190 Integer Overflow or Wraparound Numeric Error
CWE-20 Improper Input Validation Validation
CWE-345

Affected Products 1

VendorProductVersionRange
nimiqnimiq_proof-of-stake* <1.3.0

References 3

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

Remediation

  • github.com https://github.com/nimiq/core-rs-albatross/commit/d02059053181ed8ddad6b59a0adfd661ef5cd823
    Patch
  • github.com https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-6973-8887-87ff
    PatchVendor Advisory