{"id":"CVE-2026-46540","summary":"Nimiq light-blockchain: Light blockchain rebranch issue","details":"Nimiq is a Rust implementation of the Nimiq Proof-of-Stake protocol based on the Albatross consensus algorithm. Prior to version 1.4.0, when LightBlockchain::rebranch() adopts a fork chain whose tip is a macro block (checkpoint or election), it only updates self.head but fails to update self.macro_head, self.election_head, self.current_validators, or store the election header in the chain_store. This is in direct contrast with the full Blockchain::rebranch() at blockchain/src/blockchain/push.rs:504-518, which correctly updates all macro/election state when the new head is a macro block. After a rebranch to a macro block, the stale macro_head causes subsequent macro blocks pushed via push() to be verified against the wrong predecessor via verify_macro_successor(&this.macro_head). If the rebranch target was an election block, the stale current_validators causes every subsequent block to fail verify_validators(), completely stalling the light client's chain progression. This issue has been patched in version 1.4.0.","aliases":["GHSA-m3pg-qc2q-mg8c"],"modified":"2026-08-12T03:51:26.129360433Z","published":"2026-06-09T23:45:01.847Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-841"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46540.json"},"references":[{"type":"WEB","url":"https://github.com/nimiq/core-rs-albatross/releases/tag/v1.4.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46540.json"},{"type":"ADVISORY","url":"https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-m3pg-qc2q-mg8c"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-46540"},{"type":"FIX","url":"https://github.com/nimiq/core-rs-albatross/pull/3706"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/nimiq/core-rs-albatross","events":[{"introduced":"0"},{"fixed":"e156ecc4a14377eb3e4b71f340a8ae905b9864b2"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"1.4.0"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v1.3.0","v1.2.2","v1.2.1","v1.2.0","v1.1.1","v1.1.0","v1.0.9","v1.0.8","v1.0.7","v1.0.6","v1.0.5","v1.0.4","v1.0.3","v1.0.2","v1.0.1","v1.0.0","v1.0.0-rc.5","v1.0.0-rc.4","v1.0.0-rc.3","v1.0.0-rc.2","v1.0.0-rc.1","v1.0.0-rc.0","v0.24.4","v0.24.3","v0.24.2","v0.24.1","v0.24.0","v0.23.0","v0.22.3","v0.22.2","v0.22.1","v0.22.0","v0.21.1","v0.21.0","v0.20.5","v0.20.4","v0.20.3","v0.20.2","v0.20.1","v0.20.0","v0.19.0","v0.18.0","v0.17.0","v0.16.1","v0.16.0","v0.15.0","v0.14.0","v0.13.1","v0.13.0","v0.12.1","v0.12.0","v0.11.5","v0.11.4","v0.11.3","v0.11.2","v0.11.1","v0.11.0","v0.10.0","v0.9.0","v0.8.3","v0.8.2","v0.8.1","v0.8.0","v0.7.0","v0.6.0","v0.5.4","v0.5.3","v0.5.2","v0.5.1","v0.5.0","v0.4.1","v0.4.0","v0.3.3","v0.3.2","v0.3.1","v0.3.0","v0.2.2","v0.2.1","v0.2.0","v0.1.0","v0.1.0-rc.3","v0.1.0-rc.2","v0.1.0-rc.1","v0.1.0-rc.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46540.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L"}]}