CVE-2026-46540: CWE-841: Improper Enforcement of Behavioral Workflow in nimiq core-rs-albatross
Nimiq core-rs-albatross versions prior to 1. 4. 0 contain a vulnerability in the LightBlockchain::rebranch() function where adopting a fork chain with a macro block tip does not update all necessary macro and election state variables. This leads to verification failures for subsequent blocks and stalls the light client's chain progression. The issue is fixed in version 1. 4. 0.
AI Analysis
Technical Summary
The vulnerability in Nimiq core-rs-albatross (CVE-2026-46540) arises from improper enforcement of behavioral workflow in the LightBlockchain::rebranch() method. When rebranching to a fork whose tip is a macro block (checkpoint or election), the function updates only the head pointer but neglects to update macro_head, election_head, current_validators, and the election header in the chain_store. This contrasts with the full Blockchain::rebranch() which correctly updates all macro and election state. As a result, the stale macro_head causes subsequent macro blocks to be verified against an incorrect predecessor, and if the rebranch target is an election block, the stale current_validators causes all subsequent blocks to fail validator verification, stalling the light client's chain progression. This vulnerability was patched in version 1.4.0.
Potential Impact
The vulnerability causes the light client to stall its chain progression after rebranching to a macro block fork, due to verification failures against stale macro and election state. This results in denial of service for the light client, impacting availability. There is no direct confidentiality or integrity impact reported.
Mitigation Recommendations
A fix is available in Nimiq core-rs-albatross version 1.4.0. Users should upgrade to version 1.4.0 or later to resolve this issue. No additional mitigation steps are indicated.
CVE-2026-46540: CWE-841: Improper Enforcement of Behavioral Workflow in nimiq core-rs-albatross
Description
Nimiq core-rs-albatross versions prior to 1. 4. 0 contain a vulnerability in the LightBlockchain::rebranch() function where adopting a fork chain with a macro block tip does not update all necessary macro and election state variables. This leads to verification failures for subsequent blocks and stalls the light client's chain progression. The issue is fixed in version 1. 4. 0.
CVSS v3.1
Score 6.5medium
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in Nimiq core-rs-albatross (CVE-2026-46540) arises from improper enforcement of behavioral workflow in the LightBlockchain::rebranch() method. When rebranching to a fork whose tip is a macro block (checkpoint or election), the function updates only the head pointer but neglects to update macro_head, election_head, current_validators, and the election header in the chain_store. This contrasts with the full Blockchain::rebranch() which correctly updates all macro and election state. As a result, the stale macro_head causes subsequent macro blocks to be verified against an incorrect predecessor, and if the rebranch target is an election block, the stale current_validators causes all subsequent blocks to fail validator verification, stalling the light client's chain progression. This vulnerability was patched in version 1.4.0.
Potential Impact
The vulnerability causes the light client to stall its chain progression after rebranching to a macro block fork, due to verification failures against stale macro and election state. This results in denial of service for the light client, impacting availability. There is no direct confidentiality or integrity impact reported.
Mitigation Recommendations
A fix is available in Nimiq core-rs-albatross version 1.4.0. Users should upgrade to version 1.4.0 or later to resolve this issue. No additional mitigation steps are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-14T20:42:31.368Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a28a8098dd33fbd8595f127
Added to database: 6/9/2026, 11:55:53 PM
Last enriched: 6/10/2026, 12:12:07 AM
Last updated: 6/10/2026, 2:37:55 AM
Views: 7
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