CVE-2026-33471: nimiq-block has skip block quorum bypass via out-of-range BitSet indices & u16 truncation
Affects nimiq-blockSource GCVE Database
Not known to be exploited · CVSS 9.6 Critical : upgrade to 1.7.2 as a priority.
Data as of 30 Oct 2026, 16:33 UTC
- Patch
- Available – fixed in 1.7.2
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 22 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade nimiq-block to 1.7.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| crates.ionimiq-block | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
### Impact `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 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. ### Patches [The patch for this vulnerability](https://github.com/nimiq/core-rs-albatross/pull/3657) is included as part of [v1.3.0](https://github.com/nimiq/core-rs-albatross/releases/tag/v1.3.0). ### Workarounds No known workarounds.
References
- github.com/nimiq/core-rs-albatross/security/advisories/GHSA-6973-8887-87ff (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-33471 (opens in a new tab)
- github.com/nimiq/core-rs-albatross/pull/3657 (opens in a new tab)
- github.com/nimiq/core-rs-albatross/commit/d02059053181ed8ddad6b59a0adfd661ef5cd823 (opens in a new tab)
- github.com/nimiq/core-rs-albatross (opens in a new tab)
- github.com/nimiq/core-rs-albatross/releases/tag/v1.3.0 (opens in a new tab)