Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:HSummary
CVE-2026-33471 is a critical-severity Improper Input Validation (CWE-20) vulnerability in Nimiq Nimiq Proof-Of-Stake. Its CVSS base score is 9.6 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Mark-of-the-Web Bypass (T1553.005); ranked at the 12th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SC-23 (Session Authenticity) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-33471 is a vulnerability in the nimiq-block library, which contains block primitives for Nimiq's Rust implementation, specifically within the core-rs-albatross repository. The issue lies in the `SkipBlockProof::verify` function, which computes its quorum check using `BitSet.len()` before iterating over `BitSet` indices and casting each `usize` index to `u16` (`slot as u16`) for slot lookup. Prior to version 1.3.0, an attacker can supply a `SkipBlockProof` where `MultiSignature.signers` includes out-of-range indices spaced by 65536; these indices inflate the `len()` value but collide onto the same in-range `u16` slot during aggregation.
A malicious validator with low privileges (PR:L) can exploit this over the network (AV:N) with low complexity (AC:L) and no user interaction (UI:N). By crafting such a proof, the attacker can pass skip block proof verification using far fewer than the required `2f+1` real signer slots, simply by multiplying a single BLS signature by the collision factor. This results in high impacts to integrity (I:H) and availability (A:H) with changed scope (S:C), earning a CVSS v3.1 score of 9.6. Associated CWEs include CWE-20 (Improper Input Validation), CWE-190 (Integer Overflow or Wraparound), CWE-345 (Insufficient Verification of Data Authenticity), and CWE-1284 (Immutable Public Assets Without Hashing).
The patch addressing this vulnerability is included in core-rs-albatross version 1.3.0, as shown in the fix commit and release tag. The GitHub security advisory (GHSA-6973-8887-87ff) documents the issue, and no known workarounds are available.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-25054
Vulnerability Data
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…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 14 hardening rules · 5 OS baselines
V6.7.2V1.4.2V2.1.1V2.2.1
Mitigating Controls (NIST 800-53 r5) AI
Explicit requirement to protect session authenticity structurally prevents the weakness for communications.
Developer testing and evaluation can discover missing input validation through analysis or test cases.
SI-10 directly requires validity checks on information inputs, structurally preventing improper or missing validation.
Integrity verification tools detect (but do not stop) the acceptance of data lacking authenticity.
Requiring documented development standards and tools can embed input-validation practices into the engineering process.
Secure engineering principles require use of safe arithmetic constructs or language features that structurally eliminate integer overflow during calculation.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require and enforce input validation during development.
CWE-345 directly impairs RC.RP-05's verification of restored-asset integrity/authenticity, largely defeating the outcome while still leaving other restoration-confirmation steps partially viable.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Testing against a defined set of requirements and using code review plus vulnerability scanning forces validation of inputs and handling of unanticipated conditions, reducing the chance that malformed data will be accepted.
Network controls can enforce authenticated channels, reducing risk of accepting unauthentic data.
Secure network services often include authenticity checks for data exchanged over those services.
Cryptographic mechanisms directly verify data origin and integrity, preventing acceptance of unauthentic data.
Secure-coding guidelines and mandatory security testing (including code scans) compel developers to validate and sanitize inputs at design and implementation time, lowering the incidence of malformed or malicious data reaching downstream components.
Mandating input controls that include integrity checks and input validation ensures that untrusted data is examined before use, blocking the root cause of many injection and malformed-data weaknesses.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (2 rules)
- V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. prevents CWE-345
- V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
Oracle Linux 9 (1 rule)
- V-271525 OL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-345
RHEL 7 (2 rules)
- V-204447 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
- V-204448 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
RHEL 8 (2 rules)
- V-230264 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
- V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-20, CWE-345
RHEL 9 (1 rule)
- V-257822 RHEL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-345