{"cve":"CVE-2026-33471","nvd":{"published":"2026-04-22T20:16:40.317","modified":"2026-10-26T21:10:00.170","status":"Analyzed","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H","score":9.6},"cwes":["CWE-20","CWE-190","CWE-345","CWE-1284"],"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"],"products":["nimiq:nimiq_proof-of-stake"],"source":"nvd","synced_at":"2026-10-26T21:38:48.864438205+00:00"},"epss":{"cve":"CVE-2026-33471","score":0.00217,"percentile":0.12104,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-6973-8887-87ff","url":"https://osv.dev/vulnerability/GHSA-6973-8887-87ff","summary":"nimiq-block has skip block quorum bypass via out-of-range BitSet indices & u16 truncation","modified":"2026-05-05T16:02:38.268045Z","packages":[{"ecosystem":"crates.io","name":"nimiq-block","purl":"pkg:cargo/nimiq-block","ranges":["<=0.2.0"],"fixed":[]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}