CVE-2026-34068Network attack vector

Consensus forgery via omitted proof-of-knowledge validation

Published Apr 22, 2026 · Updated Apr 22, 2026

Improper signature verification in Nimiq nimiq-transaction before 1.3.0 allows remote attackers to forge macro block justifications. The staking contract accepts an UpdateValidator voting-key change when new_proof_of_knowledge is absent, so aggregate-key verification can include a rogue BLS key. Exploitation requires predicting the next epoch validator set selected by VRF; a successful forgery can make one signature appear to satisfy quorum.

CVSS severity6.8
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper signature verification in Nimiq nimiq-transaction before 1.3.0 allows remote attackers to forge macro block justifications. The staking contract accepts an UpdateValidator voting-key change when new_proof_of_knowledge is absent, so aggregate-key verification can include a rogue BLS key. Exploitation requires predicting the next epoch validator set selected by VRF; a successful forgery can make one signature appear to satisfy quorum.

The record

CVE
CVE-2026-34068
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
Nimiq
Product
nimiq-transaction
Classifications
CWE-347, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nimiq · nimiq-transactionversion=< 1.3.0

Published CVSS scores

6.8GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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