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CVE

CVE-2026-33471

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

CVE-2026-33471

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

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 is included as part of v1.3.0.

Workarounds

No known workarounds.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
9.6
-
3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H
C
H
U
-

Related Resources

No items found.

References

https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-6973-8887-87ff, https://github.com/nimiq/core-rs-albatross/pull/3657, https://github.com/nimiq/core-rs-albatross/commit/d02059053181ed8ddad6b59a0adfd661ef5cd823, https://github.com/nimiq/core-rs-albatross, https://github.com/nimiq/core-rs-albatross/releases/tag/v1.3.0

Severity

9.6

CVSS Score
0
10

Basic Information

Ecosystem
Base CVSS
9.6
EPSS Probability
0%
EPSS Percentile
0%
Introduced Version
0
Fix Available

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