nimiq-transaction: UpdateValidator transactions allows voting key change without proof-of-knowledge

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-34068: 0.20% estimated exploitation activity in the next 30 days; percentile 10.07 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact The staking contract accepts UpdateValidator transactions that set newvotingkey=Some(...) while omitting newproofofknowledge. this skips the proof-of-knowledge requirement that is needed to prevent BLS rogue-key attacks when public keys are aggregated. Because tendermint macro block justification verification aggregates validator voting keys and verifies a single aggregated BLS signature against that aggregate public key, a rogue-key voting key in the validator set can allow an attacker to forge a quorum-looking justification while only producing a single signature. While the impact is critical, the exploitability is low: The voting keys are fixed for the epoch, so the attacker would need to know the next epoch validator set (chosen through VRF), which is unlikely. Patches The patch for this vulnerability is included as part of v1.3.0. Workarounds No known workarounds.

Published by the source

22 Apr 2026, 19:22 UTC

Last modified by the source

27 Apr 2026, 16:22 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-pf4j-pf3w-95f9

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# Patch Next advisory brief: CVE-2026-34068

Advisory: nimiq-transaction: UpdateValidator transactions allows voting key change without proof-of-knowledge
IDs: CVE-2026-34068, GHSA-pf4j-pf3w-95f9
Record: https://patchnext.com/advisories/cve-2026-34068 (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io nimiq-transaction: affected <= 0.2.0

## Suggested inspection (read-only)
- crates.io nimiq-transaction: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on nimiq-transaction.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-pf4j-pf3w-95f9 (GitHub-reviewed advisory GHSA-pf4j-pf3w-95f9 lists affected ranges: crates.io nimiq-transaction >=0 <=0.2.0)

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