nimiq-block has skip block quorum bypass via out-of-range BitSet indices & u16 truncation

nimiq-block

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. 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…

Fix it

nimiq-block cargo

On 1.3.x?cargo update -p nimiq-block --precise 1.3.0
On 1.7.x?cargo update -p nimiq-block --precise 1.7.2

First seen: 22 Apr 2026
Last update: 22 Apr 2026, 19:13 UTC
Fixed in: nimiq-block 1.7.2
nimiq-block 1.3.0
Identifiers: CVE-2026-33471
CVSS: 9.6
Source: GitHub advisory
On the menu as: Rust & WebAssembly

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## nimiq-block has skip block quorum bypass via out-of-range BitSet indices & u16 truncation
Severity: critical. Patch status: patched.
Affected: nimiq-block
Fixed in: nimiq-block 1.7.2, nimiq-block 1.3.0
Ids: CVE-2026-33471

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. 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…

## Steps
1. Search every lockfile and manifest (package-lock.json, yarn.lock, pnpm-lock.yaml, requirements*.txt, poetry.lock, uv.lock, composer.lock, go.sum, Cargo.lock, Gemfile.lock) for `nimiq-block`. For each hit, compare the installed version with the fix on the same major line: nimiq-block 1.7.2, nimiq-block 1.3.0. If it's lower, give the exact upgrade command for the package manager this repo uses.

## Fix by release line
| Line | State | Fix | Until then |
|---|---|---|---|
| nimiq-block older than 1.3.0 | fixed | 1.7.2 | — |
| nimiq-block | fixed | 1.3.0 | — |

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve("CVE-2026-33471") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://github.com/advisories/GHSA-6973-8887-87ff https://github.com/nimiq/core-rs-albatross/commit/d02059053181ed8ddad6b59a0adfd661ef5cd823 https://github.com/nimiq/core-rs-albatross/pull/3657 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
https://pwned.coffee/i/nimiq-block-has-skip-block-quorum-bypass-via-out-of-rang-cve-2026-33471

Receipt

Exploitation: No known exploitation
Fix by release line: Product Affected Fixed in Source
nimiq-block (cargo) < 1.3.0 1.7.2 GitHub advisory checked 30 Oct
nimiq-block (cargo) before 1.3.0 1.3.0 CVE record (CNA) checked 30 Oct
Score: CVSS 9.6 (critical). CVSS 3.1 9.6 (CNA GitHub_M) for CVE-2026-33471
Last checked: 30 Oct 2026, 17:56 UTC

Product	Affected	Fixed in	Source
nimiq-block (cargo)	< 1.3.0	1.7.2	GitHub advisory checked 30 Oct
nimiq-block (cargo)	before 1.3.0	1.3.0	CVE record (CNA) checked 30 Oct

Sources: KEV – CVE record ✓ Vendor ✓

Sources

Wrong fix version, or a source we missed? Send it back to chef@pwned.coffee with the source, and we'll correct it here.

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