EUVD-2026-54712Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Block producer role required (PR:L); consensus integrity fully undermined (I:H); no confidentiality or availability impact; network-delivered crafted header, low complexity once role is held.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
Lifecycle Timeline
4DescriptionCVE.org
Klever-Go is the Go implementation of the Klever blockchain protocol. Prior to 1.7.20, header signature verification counts the unused padding bits of the PubKeysBitmap toward the two-thirds validator quorum. These padding bits do not correspond to any validator and are ignored by the actual BLS aggregate-signature check, so a malicious or compromised block producer can set them to reach the required quorum while gathering fewer genuine validator signatures than the protocol demands. As a result, nodes that import or intercept the header accept it as correctly signed without a real two-thirds quorum, weakening consensus safety and undermining finality. This issue is fixed in version 1.7.20.
AnalysisAI
Consensus quorum bypass in Klever-Go prior to v1.7.20 allows a low-privileged block producer to satisfy the two-thirds validator signature threshold using phantom padding bits in the PubKeysBitmap rather than genuine validator signatures. Because the BLS aggregate-signature check ignores bits beyond the consensus group size while the quorum counter does not, a crafted block header with set padding bits appears validly signed without a real supermajority, undermining blockchain finality and consensus safety. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The attacker must hold or compromise a block producer role on the Klever network, which requires staking or validator credentials (reflected as PR:L in the CVSS vector). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 4.0 score of 7.1 with vector AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N correctly reflects the attack surface: network-accessible, low-complexity, but gated behind a block producer credential (PR:L), with high integrity impact and no confidentiality or availability consequence. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade Klever-Go to version 1.7.20 or later, which is confirmed by the vendor advisory at https://github.com/klever-io/klever-go/security/advisories/GHSA-f9h7-4mmq-vgcq. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all systems running Klever-Go and document their current versions. …
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Integer overflow in Klever-Go's semi-fungible token (SFT) add-quantity path prior to version 1.7.19 allows a mint-role h
Unbounded goroutine exhaustion in Klever-Go versions 1.7.14-1.7.17 allows any connected libp2p peer to remotely degrade
Unauthenticated remote crash in Klever-Go versions 1.7.14-1.7.17 allows any network peer to terminate a node process by
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External POC / Exploit Code
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