nimiq-block has skip block quorum bypass via out-of-range BitSet indices & u16 truncation_CVE-2026-33471

{
    "lastseen": "",
    "description": "nimiq/core-rs-albatross is a Rust implementation of the Nimiq Proof-of-Stake protocol based on the Albatross consensus algorithm. `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.",
    "published": "2026-04-22T19:13:04.687Z",
    "modified": "2026-04-22T19:13:04.687Z",
    "type": "cve",
    "title": "nimiq-block has skip block quorum bypass via out-of-range BitSet indices & u16 truncation",
    "source": "GitHub_M",
    "references": "https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-6973-8887-87ff\nhttps://github.com/nimiq/core-rs-albatross/commit/d02059053181ed8ddad6b59a0adfd661ef5cd823\nhttps://github.com/nimiq/core-rs-albatross/releases/tag/v1.3.0",
    "id": "CVE-2026-33471",
    "bulletinFamily": "",
    "cwe": [
        "CWE-20",
        "CWE-190",
        "CWE-345",
        "CWE-1284"
    ],
    "cvelist": null,
    "sourceData": "nimiq core-rs-albatross < 1.3.0",
    "sourceHref": "",
    "cvss": {
        "score": 9.6,
        "severity": "CRITICAL",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
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            "privilegesRequired": "",
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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "core-rs-albatross",
    "version": "< 1.3.0",
    "vendor": "nimiq",
    "ai_description": "Skip block quorum bypass via out-of-range BitSet indices and u16 truncation",
    "ai_severity": "Critical",
    "ai_vendor": "Nimiq",
    "ai_product": "core-rs-albatross",
    "ai_version": "< 1.3.0",
    "ai_score": 9.6
}